Scottish Court of Session Decisions

OUTER HOUSE, COURT OF SESSION [2011] CSOH 19
A680/07	OPINION OF LORD HODGE in the cause VERATHON MEDICAL (CANADA) ULC Pursuer; against AIRCRAFT MEDICAL LIMITED Defender: ­­­­­­­­­­­­­­­­­________________

Pursuer: Currie, Q.C., Higgins; Maclay Murray & Spens LLP

Defender: Lake, Q.C., O'Brien; DLA Piper Scotland LLP

1 February 2011

[1] The pursuer is a company incorporated in Nova Scotia, Canada and is a specialist in the field of medical equipment. The defender is a company incorporated in the United Kingdom and is also a manufacturer of medical equipment.

[2] The pursuer is the proprietor of the European Patent (UK) 1 307 131 B1 - "Intubation Instrument" ("the Patent"), which is registered in respect of the United Kingdom. The Patent has priority dates of 7 August 2000 and 6 December 2000. The Patent has been amended in contested proceedings before the Opposition Division of the European Patent Office ("EPO"). In discussing the Patent I refer to the claims as re-numbered after the EPO's amendments.

[3] The pursuer seeks a declarator that the defender has infringed the Patent and, in particular, Claims 1, 4, 5 and 8-16 thereof. The pursuer also seeks interdict and damages, which it states at £37,000,000, which failing, an accounting for the defender's profits from its sale of the McGrath Series 5 laryngoscope. The pursuer also seeks to amend the Patent under section 75 of the Patents Act 1977 ("the 1977 Act") and Rule 55.5 of the Rules of the Court of Session and a declarator that the defender has infringed the added Claims 18 and 19. The defender counter claims for revocation of the Patent on the basis that the alleged invention was not new and, separately, that it lacked an inventive step.

[4] By interlocutor dated 28 January 2009 Lady Smith allowed parties a proof before answer on the issues of (i) infringement of the Patent, (ii) the defender's application for its revocation and (iii) the pursuer's application to amend the Patent.

[5] The parties agreed in a Joint Minute that as at 11 January 2010 the defender had "manufactured, used, kept (for disposal or otherwise), marketed, offered to dispose of/sell, and disposed of/sold Series 5 laryngoscopes in the United Kingdom" and that the defender continues to do so.

Background

(i) Endotracheal intubation

[6] A laryngoscope is, as its name suggests, a medical device for visualising the larynx. Anaesthetists and, in North America, practitioners of emergency medicine use the device to facilitate intubation of a patient, either in the context of elective surgery or in an emergency, such as a severe injury. Intubation is a means of managing a patient's airway, providing him (and I will say this only once) or her with oxygen and removing carbon dioxide and other waste products of respiration. Successful airway management is essential to such a patient's survival. In order to place an endotracheal tube in a patient's trachea (or windpipe) the medical practitioner usually needs to obtain a view of the glottis, which is the opening of the larynx between the vocal cords. Routine intubation is normally carried out on a patient who has been given anaesthetic drugs to induce general anaesthesia and neuromuscular paralysis. It is necessary to describe briefly the relevant anatomy of the patient in order to understand much of the evidence which the parties led in this proof.

[7] The safety and success of intubation depend in large measure on the obtaining of a good view of the glottis so that the medical practitioner can observe the endotracheal tube entering the larynx, whereby it is placed in the trachea which serves the lungs. Human anatomy does not make it an easy task to obtain a straight line of sight from outside a patient's mouth to the glottis. A standing patient's oral cavity is broadly on a horizontal plane ("the oral axis") while his pharynx (the cavity forming the upper part of the gullet, lying behind the nose, mouth and larynx) is close to the vertical plane ("the pharyngeal axis"). The larynx is located in front of the pharynx and so the axis from the back of the mouth ("the posterior oropharynx") to the larynx ("the laryngeal axis") of the standing patient tilts forward from the vertical as it descends. Thus the line of sight from outside the patient's mouth to the glottis must first traverse the patient's oral cavity to the posterior oropharynx and then angle forward at approximately 90º to reach the glottis. When the patient is lying on his back on the operating table in a neutral position the same angle exists but the oral axis is broadly vertical and the laryngeal axis is broadly horizontal. Patients are normally intubated under general anaesthesia; the axes are therefore generally in the latter positions when the medical practitioner starts his attempt to intubate.

[8] In order to create a direct line of sight from outside the mouth to the glottis the medical practitioner has to move the neck and head of the patient who is lying on the operating table, by flexing forward the neck on the body and then extending the head on the neck, so as to place the patient in what is known as the "sniffing position". Thereafter, the medical practitioner must insert the laryngoscope and use force to displace tissues to create the direct line of sight.

[9] At the back of the tongue there is the vallecula, which is a groove above the epiglottis, which in turn is a cartilaginous flap over the glottis. To obtain a view of the glottis the medical practitioner needs to displace the epiglottis by raising it. He can do so either indirectly or directly. The former method involves the placing of the tip of the laryngoscope into the vallecula and raising the device, thereby creating tension on the hyo-epiglottic ligament and indirectly elevating the epiglottis to expose the glottic aperture. The latter method entails the placing of the tip of the laryngoscope posterior to the epiglottis and lifting the blade on the posterior surface of the epiglottis, thus elevating the epiglottis to create the desired view.

[10] Once the medical practitioner has achieved the direct line of sight he can insert the endotracheal tube through the patient's glottis. The success or failure of intubation depends in large measure on the quality of the view of the glottis which the practitioner achieves by use of the laryngoscope. The Cormack-Lehane system, which was published in 1984, is generally used to define the quality of glottic view. It is based on four pre-defined grades of glottic view; grades 1 and 2 are respectively a full view and a partial view of the glottis. Grade 3 involves no view of the glottis but visualisation of the epiglottis and grade 4 defines the circumstance in which laryngoscopy cannot identify the epiglottis. Research reveals a success rate of almost 100% in the intubation of patients with a grade 1 or grade 2 view while a grade 4 view has a success rate of near zero. Failed intubation risks brain damage or death.

[11] The medical practitioner seeking to intubate a patient faced a serious complication if the patient had a facial, head or neck injury which hampered or prevented the adjustment of his head and neck into the "sniffing position". Medical practitioners engaged in airways management recognised the phenomenon of a "difficult airway", of which there were several definitions. Whichever definition was used, about 5%-6% of intubations carried out in operating rooms could be characterised as having moderate to severe difficulty. I do not need to discuss the various circumstances or anatomical attributes which could give rise to a difficult airway in a patient; it is sufficient to note that among the medical professionals who involved themselves in airways management there were those who took a particular interest in difficult airways. In the United Kingdom that interest was often manifested by membership of the Difficult Airways Society, which is a specialist society of anaesthetists with (in 2010) about 2,500 members.

(ii) The laryngoscope

[12] Conventional laryngoscopes consist of two parts, the handle and the blade. The medical practitioner controls the laryngoscope by holding the handle in his left hand. The handle contains batteries to power an illumination device on the blade of the instrument. The blade of the instrument is inserted through the mouth. Its distal end is placed either in the vallecula or on the posterior surface of the epiglottis, as I have described. It is the means by which the practitioner applies force to lift the epiglottis. At the priority date there were two principal types of laryngoscope in general use. One had a curved blade and the other had a straight blade.

[13] The curved blade, which was used in most hospitals in the United Kingdom, was the Macintosh blade, which was inserted paraglossally in the right hand side of the patient's mouth and which had a flange to displace the tongue. Accordingly, the blade could then traverse the oral cavity in the midline and advance until the distal end of the blade was placed either in the vallecula or on the posterior of the epiglottis. There was some disagreement between the expert witnesses as to whether curved blades were widely used for direct elevation of the epiglottis (by lifting its posterior surface) as well as for indirect elevation in the vallecula; but nothing turns on that disagreement in this case. It was not disputed that the blades could be used in either way.

[14] The other principal type of laryngoscope had a straight blade, of which the Miller blade was commonly used. In the United Kingdom, straight blades were used predominantly in paediatric cases. Typically, straight blades have a semi-circular channel which protects the undersurface of the blade from intrusion by the patient's tongue and also provides access for the insertion of the endotracheal tube. They are inserted paraglossally. A laryngoscope with a straight blade is often used for direct elevation of the epiglottis and blades designed for such use tend to have a thin flat tip that can slip under the epiglottis. Most devices can however be used for either direct or indirect elevation of the epiglottis.

[15] The other blade with which many anaesthetists in the United Kingdom were familiar was the McCoy laryngoscope, which was invented in about 1980 and had a curved blade resembling a Macintosh blade of which the distal portion was on a pivot. Once the tip of the blade was in place, the clinician could use a lever on the handle to flex the distal portion of the blade, thereby moving the epiglottis out of the line of sight.

[16] There were very many variations of both curved and straight laryngoscope blades. Some curved blades were straighter than the traditional Macintosh blade. Some straight blades had varying degrees of curvature towards or close to the distal tip. There was a wide range of laryngoscopes available on the market with differing combinations of shape, curvature, length and width. But there was, nonetheless, a well-established classification of some laryngoscopes as having straight blades and others as having curved blades.

The Patent

[17] The Patent, which I consider in more detail below, is of an intubation instrument. Paragraph 1 of the description states:

"This invention relates to endoscopic instruments, particularly to an intubation instrument, such as a laryngoscope."

It identifies as a problem with the use of common laryngoscopes the undesirability of manipulating a patient's head, particularly where he may have an injured neck or head. It seeks to avoid that problem by indirect visualisation of the larynx. That is accomplished by means of a camera located on the posterior side of the blade (or, using the language of the Patent, "arm") of the laryngoscope. In the Patent the blade of the laryngoscope has two distinct parts, namely a base portion and, extending from it at a defined angle, a lifter portion. The camera is positioned at the junction of the two parts, pointing generally towards the distal end of the lifter portion. The lifter portion has a smooth surface for engaging the patient's epiglottis.

[18] I attach as Appendix 1 to this opinion a copy of figure 7 of the Patent, which illustrates an embodiment of the device and from which the claims can be understood. Appendix 2 is a copy of figure 8 of the Patent, which illustrates the device inserted into the patient's body.

[19] Claim 1 is in the following terms:

"An intubation instrument, a portion of which is for insertion into a patient through the patient's mouth, comprising: a body (20´, 20˝) having a handle (24) attached thereto; an elongate arm (22) having a substantially straight elongate base portion (202) attached to the body (20´, 20˝) and a substantially straight elongate lifter portion (204) extending from said elongate base portion (202) at a defined angle (208), said elongate base portion having a first defined length (207), said elongate lifter portion (204) having a second defined length (205) and a smooth surface for engaging the patient's epiglottis and a distal end (210) for insertion distal-end first through the patient's mouth, said elongate arm (22) defining an anterior side positioned toward said handle and an opposite posterior side, and a viewer (80´) operably secured to said posterior side of said arm (22) substantially where said elongate base portion (202) meets said elongate lifter portion (204); characterised in that:

said second defined length (205) being about as long as first defined length (207);

said viewer (80´) being directed toward the distal end (210) of said elongate lifter portion (204); and

said viewer (80´) being a camera."

[20] The reference in claim 1 to "(20˝)" as an illustration of the body is to another embodiment of the device in claims 6 and 7 and figure 9 of the patent, in which there is a pivot at the junction between the base portion and the lifter portion which allows the operator to adjust the angle between the base portion and the lifter portion. In this action we are not concerned with that embodiment or those claims.

[21] Claims 4 and 5 are in the following terms:

"4. The intubation instrument of claim 1, wherein said viewer (80´) is a Complementary Metal Oxide Semiconductor camera.

5. The intubation instrument of claim 4, further including a display (218) operably secured to said Complementary Metal Oxide Semiconductor camera."

I attach as Appendix 3 to this opinion a copy of the diagrams, figures 11A and 11B, from the Patent which illustrate the display.

[22] Claims 8 to 16 are in the following terms:

"8. The intubation instrument of claim 1, wherein said elongate lifter portion (204) is between 3-10 centimeters long, inclusive.

9. The intubation instrument of claim 1, wherein said elongate lifter portion (204) is between 4-8 centimeters long, inclusive.

10. The intubation instrument of claim 1, wherein said elongate lifter portion (204) is approximately 6 centimeters long.

11. The intubation instrument of claim 1, wherein said angle (208) is between 5º and 85º, inclusive.

12. The intubation instrument of claim 1 or claim 9, wherein said angle (208) is between 30º and 60º, inclusive.

13. The intubation instrument of claim 1 or claim 10, wherein said angle (208) is approximately 45º.

14. The intubation instrument of claim 1, further including a light (212) operably secured to said elongate lifter portion (204).

15. The intubation instrument of claim 14, wherein said light (212) is a light emitting diode.

16. The intubation instrument of claim 1, further including a display (218) operably secured to said viewer (80´), said display (218) for viewing output from said viewer (80´)."

The law on the construction of patents

[23] Before I turn to the expert evidence which the parties have led, I summarise the law relating to the interpretation of patents which is relevant to this dispute. Section 125 of the 1977 Act states:

"(1) For the purposes of this Act an invention for a patent for which an application has been made or for which a patent has been granted shall, unless the context otherwise requires, be taken to be that specified in the claim of the specification of the application or patent, as the case may be, as interpreted by the description and any drawings contained in that specification, and the extent of the protection conferred by a patent or application for a patent shall be determined accordingly.

...

(3) The Protocol on the Interpretation of Article 69 of the European Patent Convention (which Article contains a provision corresponding to subsection (1) above) shall, as for the time being in force, apply for the purposes of subsection (1) above as it applies for the purposes of that Article."

[24] The Protocol on the Interpretation of Article 69 of the European Patent Convention provides:

"Article 1 - General Principles

Article 69 should not be interpreted in the sense that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Neither should it be interpreted in the sense that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patentee has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patentee with a reasonable degree of certainty for third parties.

Article 2 - Equivalents

For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims."

Article 2 is an addition to the Protocol which came into force in 2007. But it does not add anything to the pre-existing law of the construction of patents in the United Kingdom: Terrell on the Law of Patents (16^th ed.) at paragraph 6.50.

[25] The House of Lords in two leading cases has given authoritative guidance on the construction of patents. In Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183 Lord Diplock, with whom the other Law Lords agreed, held that a patent specification should be given a purposive construction rather than a purely literal one. More recently, in Kirin-Amgen Inc v Hoechst Marion Rousel Ltd [2005] RPC 9, Lord Hoffmann, with the concurrence of the other Law Lords, reviewed the law on the construction of patent claims. In so doing he built on and explained Lord Diplock's reference to purposive construction.

[26] In my opinion the law on the interpretation of patent claims, which is relevant to this dispute, can be summarised in the following propositions, which I derive from Lord Hoffmann's speech at pp.185-187. First, the construction of the claims of a patent is an objective exercise. It is concerned with what the reasonable person, to whom the claims are addressed, would have understood the author of the patent to be using the words in the claim to mean. Secondly, the notional addressee is the person skilled in the art who reads the specification with the common general knowledge of the art. The proper interpretation of the words of a patent is highly sensitive to the context and background against which the words are used, including the identity of, and knowledge attributed to, the skilled addressee. I discuss the concepts of the skilled addressee and the common general knowledge in paragraphs [31] to [39] below. Thirdly, the language which the patentee has used must be construed in the context of the patent as a whole and in the light of that common general knowledge. Fourthly, the skilled addressee in reading the patent assumes that its purpose is to describe and demarcate an invention. The notional addressee's interpretation is purposive only in the sense that he approaches the patent in the knowledge that it is the communication of the idea of an invention. Thus, fifthly, the language which the patentee has chosen is usually of critical importance. The words which the patentee uses in the specification, which is a unilateral document, will usually have been chosen upon skilled advice. Sixthly, because a patentee is describing something which to his mind is new and for which there is not a generally accepted definition, the skilled addressee may readily see that he must have departed from conventional use of language or included in his description some element which he did not mean to be essential. But, seventhly, one would not expect that to happen very often. A patent may, for one reason or another, claim less than it teaches or enables. And one would have to have some rational basis for concluding that the patentee had departed from conventional usage.

[27] Lord Hoffmann in Kirin-Amgen also discussed how the courts in the United Kingdom, at a time when the words in a patent were construed literally, according to their natural and ordinary meanings, had sought to prevent someone attempting to avoid infringement of the patent by making an immaterial variation in the invention described in the claims. Since the Catnic case and the Protocol on the Interpretation of Article 69, with which it was in accordance, the principle of interpretation was one which gave the patentee the full extent of the monopoly which the skilled addressee would think that he was intending to claim and no more than that extent. This protected the reasonable expectations of each side. As Lord Hoffmann observed (at p.189) restricting the monopoly in this way also protected the patentee, as otherwise the patent would be unreasonably exposed to claims of invalidity on grounds of anticipation or insufficiency.

[28] The focus therefore is on what the skilled addressee would understand the patentee to mean by the language of the claims. It is the claims which delimit the invention while the rest of the specification is for the practical information of the public: British United Shoe Machinery Co Ltd v A. Fussell & Sons Ltd (1908) 25 RPC 631, Fletcher Moulton LJ at p.650. But it is well established that the claims must be construed as part of the whole specification: Lubrizol Corporation v Esso Petroleum Co Ltd [1998] RPC 727, Aldous LJ at p.738. As Article 69 of the European Patent Convention says, the description and drawings are used to interpret the claims. The patentee's purpose is ascertained from the description and the drawings. The claims define the monopoly claimed. If the meaning of a claim is clear when construed in the light of the whole document, including the description and the drawings, the claim cannot be further cut down or extended by reference to the rest of the specification. It is also uncontroversial that the characteristic feature of a subordinate claim is treated as embraced by an antecedent claim to which it is appended, and thus guidance may be obtained from a subordinate claim on the construction of the antecedent claim. For the last two propositions see Glaverbel SA v British Coal Corporation [1995] RPC 255, Staughton LJ at p.269 and Peter Gibson LJ at p.281.

[29] In his submissions at the close of the proof, Mr Currie QC, who appeared for the pursuer, emphasised the concept of equivalents and the three-stage test which Lord Hoffmann set out in Improver Corporation v Remington Consumer Products Ltd [1990] FSR 181 at p.189. Lord Hoffmann stated:

"If the issue was whether a feature embodied in an alleged infringement which fell outside the primary, literal or acontextual meaning of a descriptive word or phrase in a claim ('a variant') was nevertheless within its language as properly interpreted, the court should ask itself the following three questions:

                                (1)     Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no?

                                (2)     Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art? If no, the variant is outside the claim. If yes?

                                (3)     Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the variant is outside the claim.

On the other hand, a negative answer to the last question would lead to the conclusion that the patentee was intending the word or phrase to have not a literal but a figurative meaning (the figure being a form of synecdoche or metonymy) denoting a class of things which include the variant and the literal meaning, the latter being perhaps the most perfect, best-known or striking example of the class."

[30] These questions, as Mr Currie recognised in his submissions, are merely guidelines and are not legal rules, for Lord Hoffmann re-considered them in Kirin-Amgen (at p.191) and stated:

"It is important to distinguish between, on the one hand, the principle of purposive construction which I have said gives effect to the requirements of the Protocol, and, on the other hand, the guidelines for applying that principle to equivalents, which are encapsulated in the Protocol questions. The former is the bedrock of patent construction, universally applicable. The latter are only guidelines, more useful in some cases than in others."

Lord Hoffmann also observed (at p.194) that:

"the invention should normally be taken as having been claimed at the same level of generality as that at which it is defined in the claims. It would be unusual for the person skilled in the art to understand a specification to be claiming an invention at a higher level of generality than that chosen by the patentee."

As a purposive construction militates against giving a word or phrase an acontextual meaning, there is no need for a general doctrine of equivalents. A trivial or minor difference between an allegedly infringing device and an element of a claim may not, on a fair reading of a claim in context, avoid infringement of the patentee's monopoly.

The law relating to the skilled addressee and common general knowledge

[31] The notional skilled addressee is central to the task of the court both in relation to the construction of a patent and also in relation to the issues of novelty, obviousness and sufficiency, which determine its validity. The notional skilled person or persons to whom the patentee addresses his patent are

"those likely to have a practical interest in the subject matter of his invention (i.e. 'skilled in the art')".

They are the notional readers of the words which the patentee chooses to use in the patent specification,

"by which he informs them what he claims to be the essential features of the new product or process for which the letters patent grant him a monopoly."

See Catnic Components Ltd, Lord Diplock at pp.242-243. I consider that it is implicit in the concept of the skilled addressee of a patent that this notional person is someone who might, but for the patentee's monopoly, be directly involved in producing a device from the patentee's invention and not merely someone who would use the device once it is created. In this regard I agree with the submission of Mr Lake QC for the defender, who referred, by way of illustration, to Dyson Appliances Ltd v Hoover Ltd (No 1) [2001] RPC 26 and Minnesota Mining & Manufacturing Co v ATI Atlas Ltd
[2001] FSR 31. In the first case, which concerned the patent of a cyclone vacuum cleaner, Michael Fysh QC held (at paragraph 34) that the skilled addressee was "a graduate or HND engineer in either mechanical or electrical engineering (probably, a team of both) with a few years' practical experience in the vacuum cleaner industry." In the latter case, which concerned a patent for sterilisation indicators, Pumphrey J held (at paragraph 30) that the skilled addressee was the maker and seller of sterilisation indicators who employed a microbiologist with interests in the relevant area and an enzymologist who could carry out the directions in the patent specification. The end user in each case, the domestic cleaner and the clinician using an autoclave, was not the skilled addressee.

[32] Parties agreed that the skilled addressee could be a team whose members possessed different skills. They were also in agreement on the qualities which the notional skilled addressee was to possess. He was unimaginative and had no inventive capacity. He had a very good background technical knowledge (the "common general knowledge" which I discuss in paragraphs [35]-[39] below). He would share the common technical prejudices or conservatism which prevailed in the art concerned. He was forgetful so that, while he had read all the prior art, he forgot one piece of the prior art before he read the next, unless it formed part of the common general knowledge or could form an uninventive mosaic with another piece or there was a sufficient cross-reference that it was justified to read the documents as one. See Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd [1972] RPC 346, Lord Reid at p.355, Technip France SA's Patent [2004] RPC 46, Jacob LJ at paragraphs 7-10, Glaxo Group Ltd's Patent [2004] RPC 43, Pumphrey J at paragraphs 27-30.

[33] Parties were also at one that the art of which the notional skilled addressee was aware could be different for the purposes of the construction and sufficiency of the patent on the one hand and the issue of obviousness on the other. In some cases the invention could be "art changing" so that, post-patent, the notional addressee's knowledge of the art in construing the patent may be different from what he is taken to have had when considering obviousness: Schlumberger Holdings Ltd v Electromagnetic Geoservices AS [2010] EWCA Civ 819, Jacob LJ at paragraphs 61-64.

[34] I would add two points. First, I accept, as Mr Lake submitted, that the skilled addressee does not represent the lowest common denominator of persons actually engaged in the field, who is deemed to possess only the knowledge and prejudices that all of them can be said to possess: Glaxo Group Ltd's Patent (supra), Pumphrey J at paragraph 32. Secondly, as Lord Hoffmann observed in Kirin-Amgen (at paragraph 78), the skilled addressee when construing the patent must be assumed to know the basic principles of patentability. In other words, he is taken to be aware in general terms of the constraints which novelty, obviousness and sufficiency place on the patentee in framing his claims.

[35] Turning to the common general knowledge, we are concerned in this case principally with the extent of the skilled addressee's knowledge of laryngoscopes in use, patent specifications, and medical and scientific papers. The concept of the common general knowledge is

"derived from a commonsense approach to the practical question of what would in fact be known to an appropriately skilled addressee - the sort of man, good at his job, that could be found in real life."

See General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1972] RPC 457 (at p.482) in which Sachs LJ gave the judgment of the Court of Appeal. In Beloit Technologies Inc v Valmet Paper Machinery Inc [1997] RPC 489, CA, Aldous LJ (at p.494) described the common general knowledge as:

"the common knowledge in the field to which the invention relates."

Thus it is not the knowledge of the people working in the field with the best facilities, whether in large hospitals with well-stocked medical libraries or in companies with patent departments: Beloit Technologies at pp.494-5. Nor, as I have said, does one descend to the lowest common denominator when looking for the knowledge of the ordinary man.

[36] In this case, as in General Tire & Rubber Co, it is clear that individual patent specifications and their contents do not form part of the common general knowledge. In relation to scientific papers, it is not sufficient that a paper is widely read by those interested in the art. In General Tire & Rubber Co (at pp.482-3) Sachs LJ approved the dictum of Luxmoore J in British Acoustic Films Ltd v Nettlefold (1936) 53 RPC 221 (at p.250) and held that a piece of knowledge disclosed in a scientific paper only becomes common general knowledge when it is generally known and generally regarded as a good basis for further action by the bulk of those who are engaged in the particular art.

[37] Mr Lake QC submitted that when the court used the legal creation of the skilled person in relation to obviousness, that notional person's reading might in certain cases be extended beyond the scope of what is the common general knowledge strictly so called. In Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd, Lord Reid (at p.355) stated:

"In dealing with obviousness, unlike novelty, it is permissible to make a "mosaic" out of the relevant documents, but it must be a mosaic which can be put together by an unimaginative man with no inventive capacity."

Keeping those restrictions - lack of imagination and uninventiveness - in mind, the courts have recognised that the skilled person may be treated as having looked at literature which is readily to hand and of which he is aware if, in real life, every unimaginative person skilled in the art would have done so as a starting point for tackling a new problem. That literature search would not involve a diligent pursuit of all leads and cross-references but only the identification of the publications which he knows and sees that he needs to use as a starting point or foundation for further work. See Nutrinova Nutrition Specialties & Food Ingredients GmbH v Scanchem UK Ltd [2001] FSR 42, Pumphrey J at paragraph 81, Ivax Pharmaceuticals UK Ltd v Akzo Nobel BV (No 2) [2007] RPC 3, Lewison J at paragraph 55. This extension covers only material, the existence of which the skilled man is aware and which he thinks is reliable to use as a foundation for further work. See also Raychem Corporation's Patent [1999] RPC 497, in which Aldous LJ, at pp.503-504, quotes with approval from the judgment of Laddie J at first instance. Mr Currie challenged the instructions which the defender had given Professor Denyer and Dr Muirhead on this matter.

[38] In Generics (UK) Ltd v Daiichi Pharmaceutical Co Ltd [2009] RPC 23, Jacobs LJ (at paragraph 27) emphasised the restrictions of, and the importance of unimaginativeness and the lack of inventive capacity in, this exercise:

"It would be wholly subversive of patents and quite unfair to inventors if one could simply say 'piece of information A is in the standard literature, so is B (albeit in a different place or context), so an invention consisting of putting A and B together cannot be inventive.' The skilled man reads each specific piece of prior art with his common general knowledge. If that makes the invention obvious, then it does. But he does not read a specific citation with another specific citation in mind, unless the first causes him to do so or both are part of the matter taken to be in his head."

[39] It is clear that such information cannot be used, with the knowledge of the content of the patent in suit, to build up a "step by step" argument in support of obviousness; that approach has been rejected by the House of Lords in Technograph Printed Circuits Ltd (See Lord Diplock at p.362). The role of this information is therefore limited. In KCI Licensing Inc v Smith & Nephew plc [2010] EWHC 1487 (Pat) (at paragraph 112), Arnold J summarised the position in these terms:

"It follows that, even if information is neither disclosed by a specific item of prior art nor common general knowledge, it may nevertheless be taken into account as part of a case of obviousness if it is proved that the skilled person faced with the problem to which the patent is addressed would acquire that information as a matter of routine."

I accept that conclusion so long as one keeps in mind (a) that it is information acquired as a matter of routine, (b) that the notional skilled person - unlike many real people to whom patents are addressed - is both unimaginative and uninventive, and (c) that the information is only a foundation for further work. In my view it does not add anything of significance to the common general knowledge in this case, nor affect the conclusions which I have reached on obviousness.

The role of expert witnesses

[40] There was no disagreement between counsel on the proper role of an expert witness in a patent case. An expert witness assists the court by educating the judge in the technology, explaining the state of the art and the meaning of technical terms. As Mummery J stated at first instance in Glaverbel SA v British Coal Corporation [1994] RPC 443,

"Evidence can be given by experts to enlighten the judge on the meaning which those skilled in the art would give to technical or scientific terms and phrases and on unusual or special meanings given by such persons to words which might otherwise bear their ordinary meaning."

He can opine on questions, such as obviousness, which are not questions of law. But the views of an expert cannot bind the court on issues which it is the task of the court to determine. He is not and need not approximate the notional skilled addressee. Thus the fact that an expert witness had certain knowledge at the priority date does not mean that that was common general knowledge. Further, it is not the personal opinion of the expert witness but the reasoning with which the expert supports his opinion that is his principal contribution to the court in its tasks of determining how the skilled addressee would interpret the claims of a patent and of assessing whether the alleged invention was novel or obvious. See Technip France SA's Patent (supra), Jacob LJ at paragraphs 12-15, SmithKline Beecham Plc v Apotex Europe Ltd [2005] F.S.R. 23, Jacob LJ at paragraphs 52-53 and Conoco Specialty Products Inc v Merpro Montassa Ltd 1992 SLT 444, Lord Sutherland at p.448.

[41] In this case I have been privileged to hear the evidence of three eminent medical practitioners and am grateful to them for the skill and care with which they sought to assist the court.

[42] Dr Ron Walls MD is Professor of Medicine (Emergency Medicine) at Harvard Medical School and Chair of the Department of Emergency Medicine at Brigham and Women's Hospital in Boston, USA. He has held academic and medical appointments at George Washington University Hospital, Washington, DC, the University of British Columbia and Vancouver General Hospital, and since 1993 at Harvard and Brigham and Women's Hospital. He has had numerous other professional duties, served on many committees, published widely, and since 2002 has been an examiner on the American Board of Emergency Medicine.

[43] As the first witness in the case Professor Walls introduced the court to the relevant anatomy, intubation devices, the prior art and the terminology used in the Patent. He also gave opinion evidence on the common general knowledge, anticipation, obviousness and infringement. I wish to pay tribute to the skilled way in which he educated me in relation to those matters. He also commented on the report of the defender's expert, Dr John Henderson. He manifested in his evidence his gifts as a teacher and his very extensive experience in education and research in relation to airway management.

[44] Dr Christopher Frerk, who was the pursuer's second witness, has been an anaesthetist for 23 years and a consultant anaesthetist at Northampton General Hospital since 1993. He has had a particular interest in airway management for about 20 years and between 2006 and 2009 was chairman of the Difficult Airway Society ("the DAS"). The DAS, as I have said, is a society of specialists who work specifically in the area of airway management. It produces a newsletter and holds workshops and an annual scientific meeting with lectures on developments in airway management. It evaluates new laryngoscopes and other airway devices. Within his hospital Dr Frerk is the lead anaesthetist for managing difficult airways. He gave evidence on anatomy, the use of laryngoscopes and other devices, the state of the art at the priority date and the common general knowledge. He also commented on the report of the defender's expert, Dr John Henderson. He was not instructed to advise on the meaning of the Patent but offered certain views on that matter on cross-examination.

[45] Dr John Henderson, whom the defender led as its expert medical witness, was an anaesthetist from 1970 until his retirement in August 2010. He trained in the United Kingdom and in the United States and was consultant anaesthetist at the Western Infirmary and Institute of Neurological Sciences, Glasgow from 1978 to 1983 and at the Western Infirmary, Glasgow from 1983 until his retirement. He has had a special interest in airway management throughout his career, has been involved in the DAS, published many papers and contributed chapters on airway management to leading textbooks on anaesthesia or airway management and is the patentee of the Henderson laryngoscope, which I discuss below. Dr Frerk described Dr Henderson as "an acknowledged airway expert in the UK" and part of the group which authored the DAS guidelines. Dr Henderson also gave evidence on anatomy, the use of laryngoscopes, prior art, the identity of the skilled addressee, the common general knowledge, the meaning of the Patent, novelty and obviousness, and infringement.

[46] I also heard the evidence of a medical device engineer and a physicist with expertise in optoelectronics, both of whom were very experienced in their respective fields of expertise.

[47] Dr Colin Roberts, whom the pursuer called, is a very experienced medical device engineer with over forty years experience. He served as Chair of Biomedical Engineering and Foundation Professor of Medical Engineering at King's College Hospital, London and has had experience in industry, the National Health Service and academia. He gave evidence on the identity of the skilled addressee, the common general knowledge in the healthcare and medical device industry, infringement and the defender's challenge to the validity of the Patent.

[48] Dr Ian Muirhead, whom the defender called, is chief executive officer of Ambicare Health Limited. He has a degree and a doctorate in physics as well as a Master of Business Administration and has twenty years experience in the field of optoelectronics, related technology and its applications including the development of Charge Coupled Device ("CCD") and Complementary Metal Oxide Semiconductor ("CMOS") cameras. He gave evidence on the identity of the skilled addressee, the common general knowledge, and the sealing of cameras within medical devices.

[49] I also had before me two reports from Professor Peter Denyer, who was to give evidence on camera technologies, and in particular CMOS camera technology, before and at the priority date and their application to endoscopy, including in laryngoscopes. Unfortunately he took ill at the outset of the proof and was unable to give his evidence. Sadly he died during the proof. While I read his reports in my preparation for the proof, I have had regard to them only to the extent that Professor Colin Roberts and Dr Ian Muirhead commented on them in their evidence. I have not otherwise had regard to Professor Denyer's evidence in framing this opinion as it was not tested by any cross-examination. The defender led the evidence of Dr Ian Muirhead in his place.

[50] In their submissions counsel for both parties criticised the evidence of the other's expert witnesses, particularly for straying beyond the expert's remit by giving their personal opinions on the meaning of the claims. I consider that it is probably inevitable that experts wander into prohibited evidential territory in the course of their oral evidence. The court can deal with that relatively easily by keeping in mind the purpose and limitations of such expert evidence. Mr Currie criticised Dr Henderson for giving subjective opinions based on his own experience, he being an inventor of a patented laryngoscope and significantly more qualified than the skilled addressee, and for failing to concentrate on giving guidance on the knowledge and approach of the skilled addressee. He also criticised him for failing to back up certain assertions with reasoning and for showing in his oral evidence a lack of familiarity with the detail of the Patent. Mr Currie also criticised Mr Muirhead's evidence as being of peripheral relevance because it was based on his own experience in the field of optoelectronics. Mr Lake did not make such general criticisms of the pursuer's experts but criticised certain specific aspects of their evidence which I will address in context. It is correct that in his oral evidence Dr Henderson on occasion expressed personal views, and that Dr Walls in particular was generally more assiduous in his oral evidence in backing up his opinions with references to literature. But Mr Currie's criticism in my opinion does not give sufficient weight to Dr Henderson's detailed citation of medical literature in the appendices which accompanied his reports; and other witnesses also stated personal views in the course of their oral evidence. In any event, with each expert witness it is not his personal opinion but his reasoning to which I have to pay regard. Nor is it necessary or desirable that an expert should approximate to the notional skilled addressee: Technip France SA's Patent (supra), Jacob LJ at paragraph 12. The wholly uninventive and unimaginative expert, if such a person exists, might not make a good teacher of the court.

The prior art

[51] In considering the prior art in this part of my opinion I emphasise that I am not addressing the common general knowledge at the priority date. Most of the devices, which I now discuss, are relevant to the defender's challenge to validity on the ground of anticipation or obviousness. It is not disputed that most of the devices which I describe were not part of the relevant common general knowledge at that time and therefore are of no relevance to the proper construction of the claims in the Patent. Those which are not part of the common general knowledge are relevant to the challenge to its validity on the ground of anticipation or obviousness only in each instance as a specific item of prior art in a direct comparison with the patent in suit. I consider the common general knowledge in relation to this case in paragraphs [84] to [97] below.

[52] In 2000 most practitioners using laryngoscopes whether with a curved or straight blade, established a direct line of sight to the glottis through manipulation of the patient's head and neck. This was successful in approximately 98% of intubations. There were many variations of such blades but the intubation equipment in most hospitals in the developed world included such curved or straight blades. Most of the laryngoscopes which were available at the priority date were invented by and named after clinicians, who had identified and sought to remedy specific problems with direct laryngoscopy encountered in their practice. In about 1998 Dr Henderson himself designed and patented a straight blade with a bead at its distal end which was thereafter manufactured by Karl Storz GmbH & Co KG.

[53] The principal alternative means of intubation, which could be used when difficulty in intubation was foreseen, was a flexible fibre-optic bronchoscope or laryngoscope. The patient, who remained awake and in an upright position, was given topical anaesthesia and was sedated. When using a flexible fibre-optic laryngoscope, the medical practitioner inserted the flexible fibre-optic cable via the patient's mouth into the pharynx to illuminate and obtain a view of the glottis, observing its progress by means of an eyepiece on the proximal end of the fibre-optic cable. The practitioner then passed the cable through the vocal cords and inserted an endotracheal tube, which had been placed over the fibre-optic cable, into the trachea. Only a minority of practitioners was skilled in the use of flexible fibre-optic laryngoscopes.

[54] At the priority date there were several rigid fibre-optic laryngoscopes available on the market, but they were not widely used. An advantage of the rigid fibre-optic laryngoscope over the flexible version was that the former could more readily be used on an anaesthetised patient lying on an operating table. The underlying idea of the rigid fibre-optic laryngoscope was to insert a fibre-optic scope into a patient on a rigid introducer and avoid the difficulties involved in displacing the tongue and manoeuvring a flexible cable inside the patient. Three such devices were discussed in evidence.

[55] First, the Bullard laryngoscope was the subject of US patent 4,086,919 and was filed in 1976. It comprised a handle with a blade which curved through approximately 90º in a way which generally conformed to the curvature of the passageway from the entrance of the mouth to the epiglottis so as to place the distal tip of the blade in a position to elevate the epiglottis. Attached to the blade were fibre-optic cables for transmitting light to the distal end of the blade and for transmitting visual images from that area to an eyepiece, which in the patent drawings was located at the proximal end of the blade. The patent identified as the problems of the prior art which the device sought to address (i) the need forcibly to manipulate the head and neck, (ii) contact with and damage to the patient's upper teeth, and (iii) difficulty in visualising the glottis if a patient had physical malformations of the jaw or tumours of the throat. Dr Walls acknowledged on cross-examination that the first problem was essentially the same as that which the Patent also identified. The Bullard patent described the device as involving an improved laryngoscope blade for use in indirect visualisation of the glottis. In essence the invention was an anatomically-shaped blade carrying fibre-optic cables on its posterior surface, which permitted the indirect visualisation of the glottic aperture and the larynx.

[56] In 1993 Dr Bullard filed a further patent application for a laryngoscope with an extendable tip to the blade and US patent number 5,381,787 was granted in 1995. The operator of the laryngoscope could control the tip of the Bullard blade by extending or contracting the tip extension by means of an actuator. Further, at some unspecified time there was manufactured a plastic tip which could snap on to the tip of the Bullard blade and thereby extend the length of the distal end of the blade. I attach as Appendix 4 to this opinion a photograph of the Bullard laryngoscope with the plastic tip extension.

[57] Secondly, there was the Upsherscope. This laryngoscope became available in about 1995 and resembled the Bullard laryngoscope in its use of a C-shaped curved blade which conformed generally to the anatomy of the mouth and pharynx. It had a fibre-optic viewing channel similar to that of the Bullard on the posterior of the blade and an eye piece, which was designed to be used with a camera, which extended outwards from the junction of the handle and the blade at about 60º to the handle. It also had a channel for directing the endotracheal tube so that it could be inserted into the windpipe from the distal end of the blade.

[58] Thirdly, the Wuscope was a rigid laryngoscope with a smoothly curved, anatomically-shaped, blade which had a channel into which the operator could place a flexible fibre-optic nasopharyngoscope and another channel for the insertion of the endotracheal tube from the distal end of the blade. It was developed in the later 1990s but gained only limited clinical use. Independent studies suggested that, while it obtained good glottic views in patients whose head and neck could not be manipulated, it was costly to acquire and complex to assemble and use, requiring the operator to acquire new skills.

[59] A different approach to the difficulty of seeing round the angle between the oral axis and the laryngeal axis was an invention by Dr Bellhouse, which was manufactured as the Belscope. The UK Patent Application number 2,086,732A was filed on 3 November 1981. It also sought to address the problems of how to avoid the manipulation of the patient's head and neck and how to intubate a patient with gross anatomical abnormality. The patent described a laryngoscope blade comprising two substantially straight portions which were angled in respect of each other to form a generally V-shaped blade. The angle subtended by the two portions of the blade was stated to be between 120º and 150º, and more appropriately 135º. Although expressed differently, these angles, as Dr Walls and Dr Henderson acknowledged, were the same as those stated in claims 12 and 13 of the pursuer's Patent. The patent envisaged that, in a preferred embodiment, the proximal and distal portions of the blade would be approximately the same length.

[60] The Bellhouse patent taught that the laryngoscope could be used to obtain a direct line of vision of the glottis. It also envisaged the optional use of transparent prism located on the posterior surface of the portion of the laryngoscope blade proximal to the handle and extending to the junction with the portion leading to the distal tip to provide an indirect method of viewing the trachea. The prism allowed light to be refracted from the larynx so as to enable the operator to see the glottis in a line of sight along the proximal portion of the blade. The patent also in figure 15 included a perspective view of a curved blade which might be used with the prism. There were difficulties in using the prism and the patent acknowledged that the prism did not allow a panoramic view of the glottis.

[61] Dr Bellhouse, in an article in "Anesthesiology" in 1988, commented that the Belscope, which was the laryngoscope made in accordance with the patent, was used very much like a straight-bladed laryngoscope, and in the majority of cases, there was no need to use the prism. Benumof, "Airway Management" (1996 ed.) also described the Belscope as being used much like a conventional straight laryngoscope blade in the majority of laryngoscopies. In correspondence in "Anesthesiology" in 1992 Dr Ruth M. Mayall disclosed that she had used the Belscope repeatedly without having to use the prism. It was clear that the Belscope was used predominantly for intubation by direct line of sight and that the prism was rarely needed.

[62] The Bellhouse patent referred to an earlier invention by Ephraim S. Siker MD, which he described in an article in "Anesthesiology" in January 1956. This invention was of a modified laryngoscope blade divided into three generally straight portions with a stainless steel mirror on the concave surface of an interposed middle portion through which the proximal and distal portions joined at an included angle of 135º. The anaesthetist placed the Siker laryngoscope in the patient's mouth and positioned it so that the mirror was directed towards the glottis. Manipulation of the blade to expose the glottis gave the anaesthetist an inverted and somewhat distorted image of the glottis in the mirror. The Bellhouse patent described the Siker laryngoscope as follows:

"In 1956 Siker produced a laryngoscope blade which was angulated or V shaped having an included angle of 135º. However this blade was generally C shaped in cross section having an overhanging roof portion which obscured direct vision of the larynx. Siker proposed using his blade with a mirror but it was found that his laryngoscope was generally not practicable."

[63] Another method of obtaining a better view of the glottis involved the use of a camera. Several devices used a camera for this purpose.

[64] One such was an invention by Dr Gordon George (United States Patent number 5,363,838) which was issued on 15 November 1994. It entailed an intubating scope with a malleable tube for use alongside a standard laryngoscope blade and handle. The scope had a camera, which was located either at the proximal end of a fibre-optic tube in the scope or at the distal end of the scope, and a lightweight portable screen which was connected to the scope and could be placed on the patient's chest or held by an assistant of the practitioner who carried out the intubation. If the camera was located at the distal end of the stylet the patent envisaged that it would be in the form of a computer chip or other type of integrated circuit. The objects stated in the patent included facilitating visualisation of the trachea and offering a device whose use was easily learned. Its objects did not include reducing or eliminating the need to manipulate the patient's head and neck.

[65] Another invention involving a camera was by Dr Jonathan Berall (United States Patent number 5,827,178) dated 27 October 1998. It comprised a laryngoscope with a straight blade and a camera mounted on the posterior surface of the blade close to its distal end. The camera was connected to a lightweight portable television screen, preferably mounted on the handle. The pursuer's Patent (in paragraph 8) described the invention in these terms:

"Inventors have attempted to overcome these problems with known laryngoscopes" [i.e. the need to manipulate the patient's head and neck and the blocking by tissue of the practitioner's line of sight for inserting straight devices] "by attempting to improve the practitioner's view during insertion. For example, Berall includes a camera mounted in the vicinity of the distal end of the blade and a viewer mounted on the laryngoscope, such that the practitioner has a simultaneous line of sight and camera view during insertion. However, such a camera view positioned toward the distal end is often unprotected from tissue and debris, and becomes easily blocked. Moreover, such positioning is usually too close to offer the practitioner a helpful perspective to facilitate proper insertion and alignment of the laryngoscope and endotracheal tube within the larynx. Also the straight blade remains difficult to insert."

[66] Another was the invention of Dr Robert Wood (United States Patent number 5,800,344), which was called a video laryngoscope, and was dated 1 September 1998. The patent described a laryngoscope with an image sensor assembly mounted on it for providing video imaging of the patient's airway passage during use of the laryngoscope. The video camera (or, in the language of the patent, image sensor and lens) was mounted on the posterior surface of the blade, which could be a straight blade with an elbow towards the distal end or a curved blade. The patent taught that the image sensor was to be located at a distance from the tip of the blade to avoid tissue, which surrounded the area with which the tip was in contact, interfering with the operation of the image sensor. It referred to the possible use of, among others, CMOS or CCD technologies in the image sensor. In one embodiment of the invention a track was formed on the posterior or convex surface of an elbow or a curved blade and the image sensor was able to be moved on that track. This enabled the clinician, while operating the laryngoscope in a patient, to adjust the distance between the image sensor and the target object by moving the image sensor back and forth along the track, and thereby adjust the view field of the image sensor to provide adequate viewing of the region of interest.

[67] Appendices 5 and 6 to this opinion are copies of drawings from the Wood patent showing the video camera on a straight blade (figures 2 and 3) and the moveable camera on a curved blade (figures 4 and 5).

[68] In the pursuer's Patent the Wood device is described thus (in paragraph 9):

"Another attempted improvement to known laryngoscopes involves contouring the blade as shown in U.S. Pat. No. 5,800,344 to Wood ('Wood'), and slidably securing an image sensor along such a blade to facilitate viewing. However, to be properly inserted, such devices still require undesirable manipulation of the patient's head and neck."

[69] The Patent also referred to a laryngoscope patented by Corazelli (United States Patent number 4,360,008) which offered an elongate, substantially straight blade. This laryngoscope did not have a camera or other viewer on it. The Patent described the invention (in paragraph 10) in these terms:

"To facilitate insertion of these types of known laryngoscopes, some inventors have added moving tips to the blades as shown in Corazelli, Jr. However, these tips are generally too small to adequately support the epiglottis, and they still require the practitioner to insert an elongate straight or substantially straight blade, thereby required [sic] undesirable manipulation of the patient's head and neck."

[70] In 1999 Markus Weiss MD, Professor of Anaesthesiology at the University of Zurich, published an article in the Internet Journal of Anesthesiology entitled "The Video-Intubating Laryngoscope". In that article he described how a disposable plastic Macintosh laryngoscope had been modified by making a bore hole from the bottom of the handle through the lateral flange towards the tip and inserting an ultrathin video-endoscope into the bore hole. The anaesthetist could use the device either to achieve a direct line of sight or to obtain indirect laryngoscopic visualisation of the glottis by attaching the proximal end of the endoscope to a video camera and observing the output of the video camera on a monitor. The article also displayed, in figure 2, a disposable Macintosh laryngoscope in which the distal portion of the blade had been angulated upwards at about the point where the lens of the endoscope was located within the posterior of the blade. This device was known as the angulated video-intubating laryngoscope ("AVIL"). Dr Weiss recorded that the device could be used for both routine and difficult tracheal intubation and that it might be a helpful tool to manage difficult laryngoscopy as it provided an indirect visualisation of the vocal cords. He stated:

"In situations where direct visualisation of the cords is impaired, the VIL allows to overcome the obstructed view to the larynx using conventional intubation technique and the video view around the curvature of the blade.

Preliminary limited experiences in patients with direct laryngoscopic view Grade II or III (Classification by Cormack and Lehane) showed, that the video-display from the distal blade gives a better view of the cords and the patients were intubated under monitor control without forced laryngoscopy or head-neck manipulations."

[71] Finally, in December 1998, Moritex Corporation, a Japanese enterprise, filed an application for a patent (JP 2000-175867) with a disclosure date of 27 June 2000 for a laryngoscope with a curved blade, on the posterior surface of which was located a video camera which provided an indirect visualisation of the larynx on a monitor. The patent narrated (in paragraphs 6-9) the problems which the invention addressed, namely the need to obtain a detailed view of the larynx, which a user often could not get using fibre-optic cables, and the difficulty of controlling the laryngoscope when handling heavy and relatively rigid fibre-optic cables. The use of a camera in the blade gave greater resolution to the images of the larynx which could be transmitted to the monitor by means of a light flexible signal wire. Appendix 7 to this opinion is a copy of figures 1-3 of the Moritex patent. The diagrams showed a laryngoscope with a curved anterior blade and a camera on the posterior surface. The lens of the camera was shown to be distal of the midpoint of the blade and, when inserted in a patient, providing a view from the back of the tongue towards the larynx. It was clear from the patent's description of prior art that the invention was designed to improve the performance of laryngoscopes both in the observation of the interior of the larynx for diseases and in intubation of the trachea.

The skilled person/skilled addressee

[72] Parties did not agree on the identity of the skilled addressee. Their disagreement on the identity and experience of the clinician addressee did have an impact on the scope of the common general knowledge. Otherwise their disagreements did not have any material bearing on the proper construction of the Patent or its validity.

[73] Mr Currie submitted that the skilled addressee was a clinician involved in carrying out and supervising the intubation of patients and that he would involve a medical device engineer in creating the device. In the United Kingdom the clinician would usually be an anaesthetist. In the United States he might be an emergency physician, an anaesthesiologist, a critical care physician or a paramedic. The clinician would take the lead as it was evident that for many years before the priority date it had usually been clinicians who invented new laryngoscopes. The clinician would lead the design process because of his knowledge of intubation, anatomy and existing devices which were generally known to such clinicians. The clinician, however, would be likely to need the services of a medical engineer to assist with the technical aspects of achieving the desired device.

[74] Mr Currie founded on the evidence of Professor Roberts in his submission that the medical device engineer would be a clinical technologist employed in a hospital rather than a graduate medical engineer, as the latter would be likely to be more inventive and thus not fit the mould of the skilled addressee. He submitted that the NHS employee would be trained to the equivalent of HNC or HND or foundation degree level in mechanical engineering or electronics and would have experience in a hospital workshop repairing defective equipment. He would carry out the clinician's instructions faithfully. If the notional medical device engineer were someone employed in the medical device industry, it was likely that that person would have received further training in topics such as engineering design, production processes and marketing. But, wherever the notional engineer addressee was employed, he would not have any training in anatomy or physiology, would not have used a laryngoscope, and would not have experience in designing or manufacturing endoscopes or laryngoscopes.

[75] Mr Lake submitted that the skilled addressee would be a team which would be engaged in designing and producing a laryngoscope intended to address the problems of difficult laryngoscopy. That team would comprise a clinician, a medical device engineer and a camera engineer. The clinician would be a newly qualified consultant anaesthetist who had an interest in the management of difficult airways. If that were incorrect, the clinician would be a newly qualified consultant anaesthetist (without that particular interest).

[76] In support of the contention that the consultant anaesthetist would have an interest in managing difficult airways, Mr Lake pointed out that the Patent identified as the problems which it addressed (i) the undesirability or impossibility in certain cases of manipulating the patient's head and neck, (ii) the blockage of the direct line of sight by the patient's tissue, and (iii) where the camera was located close to the distal end of a laryngoscope blade, the difficulties of blockage by tissue and the inability to obtain a perspective view. Because difficulty in obtaining a view of the glottis led to difficult intubation or difficult airways, the Patent was addressing principally the problem of difficult airways. He acknowledged that the device could be used for straightforward laryngoscopy and that all anaesthetists might be interested in using it if it were available, as Dr Walls had pointed out, but that was not the problem which the Patent addressed.

[77] The skilled addressee would include a medical device engineer as the clinician could not solve the problems by creating a new device without involving such a person. Whatever had been the position in the past, by the priority date the increased demands of regulation of medical devices under Council Directive 93/68/EEC of 22 July 1993 meant that the clinician would have been likely to involve an engineer from a medical device company. Dr Frerk recognised that the Directive had caused a shift towards the increased involvement of medical device companies in developing new instruments before the priority date. Such a person would have higher qualifications than the engineers about whom Professor Roberts spoke. Founding on the evidence of Dr Muirhead, Mr Lake submitted that the engineer in a medical device company would probably have either (i) a physics degree, or a mechanical or electrical engineering degree, followed by an MSc, (ii) a product design degree followed by experience in a design house, or (iii) a degree in biophysics or biomedical engineering.

[78] In relation to the camera technician, Mr Lake submitted that, if the medical device engineer did not have the skills of a camera technician, he and the clinician would bring such a technician into the team once they appreciated that cameras might be useful in a laryngoscope: see, for example, Schlumberger Holdings Ltd v Electromagnetic Geoservices AS (supra), Jacob LJ at paragraph 71. Dr Muirhead had agreed with Professor Denyer's assessment that the camera technician would know of CMOS and CCD products available in the market, and their potential for use, or could gain access to such products and would also understand what lens would be required to create the desired view. The pursuer had not challenged that evidence.

[79] I accept that the skilled addressee in this case is not any clinical user of a laryngoscope. Taking the circumstances in the United Kingdom as a model, I accept that the clinician addressee would be a newly-qualified consultant anaesthetist. The evidence of both Dr Frerk and Dr Henderson supported that view, although Dr Frerk did not pin his colours to the anaesthetist being a consultant. While I accept Dr Walls's evidence that the pursuer's product, the Glidescope, is suitable for everyday use and is used for that purpose, that does not mean that the Patent is addressed to every anaesthetist. Both Dr Frerk and Dr Henderson also spoke of the existence in most hospitals of a consultant anaesthetist with a special interest in airway management. I accept also that the skilled addressee would be someone who had an interest in difficult airways; the notional addressees are not every user of the device but those who might be interested in how the invention would be put into effect as a device: see paragraph [31] above and also Terrell on the Law of Patents at paragraph 6-32. It is consistent with this approach that, when considering the question of obviousness, the skilled person is treated as "at least sufficiently interested to address his mind to the subject and consider the practical application of the information which he is deemed to have." - Windsurfing International Inc. v Tabur Marine (Great Britain) Ltd [1985] RPC 59, Oliver LJ at p.73. It is also relevant to consider the terms of the patent to see what assumptions the patentee makes about the attributes and abilities of the addressee.

[80] The fact that the inventors of patented laryngoscopes have in the past usually been clinicians does not mean that every anaesthetist is the skilled addressee of a patent. Anaesthetists in the United Kingdom, as Dr Frerk explained, had very little input into the equipment which their hospital purchased and normally were aware of products only when they came on to the market. The law provides that the skilled addressee would not be inventive or imaginative; but in my view, to be an addressee, he would be interested in what others invent to improve laryngoscopy, if he were to be part of a team which constructed a laryngoscope. He would not actually read patents, as a matter of course or ever, but would have more interest in the problems of laryngoscopy than the average anaesthetist. Such a person would be much more likely to be involved in the production of a new device than others in the profession. He would also usually have an interest in difficult airways and in the problems addressed in the Patent. An inability to manipulate an injured person's head and neck is one possible cause of difficult airways. Many people who have such an interest in the United Kingdom are members of the DAS. The society was formed in 1995 against the backdrop of concerns about the safe management of patients who proved difficult to intubate and growing public intolerance of death or injury while under medical care. In the same year the Society for Airway Management was formed in the United States. But the DAS is a small sub-set of the profession. Dr Frerk estimated that of 10,000 anaesthetists in the United Kingdom, only about 2,500 were members of the DAS and that at the priority date the DAS had only about 500 members. In my opinion the skilled addressees at the priority date would not necessarily be confined to members of the DAS but that the common general knowledge of DAS members would be a better guide to the knowledge of the skilled addressee than that of the anaesthetists' profession as a whole. I therefore accept Dr Henderson's evidence that the skilled addressee would be a newly-qualified consultant anaesthetist who has an interest in airway management working with a medical device engineer.

[81] I accept that historical practice shows that the clinician would initiate the process of creating a device and would involve the medical device engineer only once he had a reasonably clear idea of what he wanted to create. The engineer would have the qualifications and experience of an engineer working for a medical device company as the requirements of the Medical Devices Directive made it likely that, by the priority date, such a person would be involved in producing the device. The notional uninventiveness of the skilled addressee does not require the court to assume that his qualifications approximate to a real person who might have that uninventiveness. The skilled addressee is suitably qualified to give effect to the teaching of the Patent. I also accept Dr Frerk's evidence that most hospitals at the priority date did not have a medical device engineer who could assist the clinician in constructing the device. Thus I accept that the clinician would consult a medical device engineer working in industry who would have the appropriate qualifications to work there. As laryngoscopes involve electronics, at least in the light source, it is sensible to assume that the medical device engineer would have some experience of electronics.

[82] I accept that the Patent envisaged that its addressee would include a medical device engineer who had some knowledge of camera technology or a camera engineer. The Patent, in paragraph 51, refers to CMOS and CCD cameras and identifies known manufacturers. In my opinion not much turns on the involvement of a camera engineer in the team as both parties accepted that a team involving a clinician and medical device engineer at the priority date could obtain the relevant cameras in the market or readily find a camera manufacturer which could adapt existing camera technology for that purpose.

[83] As I have said, I am not persuaded that much turns on the differences between the parties on the issue of the identity of the skilled addressees. However well-qualified the notional skilled addressee is taken to be, he is both unimaginative and uninventive. The principal effect of my findings is that they extend the common general knowledge of the clinician in the team in relation to difficult airways. But, as I seek to set out in the following sections, I am not persuaded that that extension has a material effect on the construction of the Patent or its validity.

The common general knowledge

[84] Mr Currie submitted that the common general knowledge of the skilled addressee who was a clinician would include, so far as relevant, knowledge of only a very limited number of laryngoscope blades. In both the United Kingdom and the United States it would include knowledge of the Macintosh laryngoscope and the technique for its use. In the United States it would also include familiarity with conventional direct laryngoscope blades such as the Magill and Miller laryngoscopes. The Magill, which was invented in 1920, has a straight blade with a curved tip; the Miller, which was invented in 1941, has, as I have mentioned, an essentially straight blade. It would also include familiarity with the McCoy laryngoscope. It would include knowledge of the existence and availability of flexible fibre-optic laryngoscopes, including the placement of the viewer at the distal end of the scope, but not the skills to use such laryngoscopes. Miller-type blades were also common in, and McCoy blades kept in a minority of, emergency departments in the United Kingdom. The skilled addressee in the United Kingdom would be aware of standard textbooks such as Aitkenhead & Smith, "Textbook of Anaesthesia" (3^rd ed.) and, in the United States, of standard textbooks such as Roberts and Hedges, Rosen and Tintinalli.

[85] Mr Currie submitted that the clinician addressee would not be aware of other laryngoscope blades, including the Belscope. He would not know the features of the Bullard or any other rigid fibre-optic laryngoscopes nor have experience in their use. Nor would he be aware of specialist textbooks such as Benumof's "Airway Management", Finucane's "Principles of Airway Management", Ward's "Anaesthetic Equipment", Latto & Vaughan's "Difficulties in Tracheal Intubation" and Barash's "Principles of Airway Management" (3^rd ed.) (2001), or review articles from all the main medical journals dealing with anaesthetics and airway management. He would not be familiar with particular patents, the concept of indirect laryngoscopes, camera and lens technology or the use of CCD or CMOS cameras in endoscopy.

[86] If it were correct to identify the skilled addressee with anaesthetists and other users of laryngoscopes, as the pursuer submitted, there was support for the view that their common general knowledge was restricted to the devices which Mr Currie listed or extended to only a limited knowledge of the existence of rigid fibre-optic laryngoscopes and other devices. Dr Walls suggested that the skilled person might have heard of the Bullard but would not have been familiar with its features. There was evidence from an editorial article by Dr R. A. Mason in the British Journal of Anaesthesia in 1998 that only 37% of anaesthetics departments in the United Kingdom offered any formal airway training and an article, to which I refer below, by Dr Edward T. Crosby and others in the Canadian Journal of Anaesthesia in 1998 disclosed the limited availability of structured training in airway management in Canada. A report by Dr Richard M. Levitan on a survey of difficult airway management in academic emergency departments in the United States showed that 49% of respondents had never used anything other than a direct laryngoscope for tracheal intubation although 64% of departments had a flexible fibre-optic laryngoscope and 6% a rigid fibre-optic device as alternative intubation devices. In the United Kingdom in 2000, there was evidence in an article by Dr T. Morton and Others in "Anaesthesia" that while all emergency departments had a Macintosh blade and 64% had a Miller-type blade, only 5% had a flexible fibre-optic bronchoscope. Both Dr Frerk and Dr Henderson suggested that if an anaesthetist identified a patient who was likely to be difficult to intubate, he would normally enlist the help of an expert in dealing with difficult intubation.

[87] It was not disputed that at the priority date the ordinary consultant anaesthetist in the United Kingdom would only have skills in and be likely to use direct laryngoscopes, being the Macintosh and paediatric straight blades. I also accept Dr Walls's evidence that in the United States many emergency physicians had never used a device other than direct laryngoscopes to assist with tracheal intubation. But that in my view is beside the point. I am satisfied for the reasons discussed in the previous section that the skilled clinician addressee is not the whole anaesthetist profession but a sub-set with a greater interest in airway management as it is from that sub-set that the overwhelming majority of those interested in improvements to the performance of airway management could be found.

[88] For that reason I accept the evidence of Dr Henderson that it would have been part of the common general knowledge that there had been attempts to obtain an indirect view of the glottis from the pharynx, behind the tongue. It was not disputed by the pursuer that there would have been an awareness of the flexible fibre-optic bronchoscope. But I am also persuaded that the existence and purpose of the Bullard laryngoscope and other anatomically-shaped rigid fibre-optic laryngoscopes would also have been within the common general knowledge of the relevant group of anaesthetists.

[89] Some but not all hospital libraries stocked the leading textbooks on airway management at the priority date. The leading textbooks on airway management included the following. Latto & Vaughan, "Difficulties in Tracheal Intubation" (2^nd ed.) (1997) in chapter 6 described both the Bullard laryngoscope and the Belscope and recommended that a clinician should have available the Macintosh, blade, the Belscope and the McCoy blade. Dr B. Finucane, "Principles of Airway Management" (1996), in chapter 8 ("Difficult Intubation") also discussed and illustrated the Belscope and the Bullard and fibre-optic bronchoscopy and recorded the recommendation of the American Society of Anesthesiologists that every difficult airway kit should include fibre-optic intubation equipment. Dr Sheila Cooper in chapter 20 of J. L. Benumof, "Airway Management" (1^st ed.) (1996) discussed and illustrated among other instruments the Belscope and the Bullard laryngoscope and presented the latter as an indirect fibre-optic laryngoscope for use in dealing with patients who had immobile or unstable cervical spines. "Ward's Anaesthetic Equipment" (4^th ed.) (1998), which was widely used by trainees and as a reference book, in chapter 9 discussed and illustrated the Bullard laryngoscope, referring to it as a means of avoiding movement of the neck and head. It also discussed and illustrated the Upsherscope, which operated on similar principles.

[90] I am not persuaded that the detail of those texts was part of the common general knowledge but, for the reasons discussed below, I consider that they would have contributed to an awareness within the relevant sub-set of the profession of the existence of devices such as the Bullard and other anatomically-shaped rigid fibre-optic laryngoscopes and I conclude that that awareness was part of the common general knowledge. While several of those texts referred to the Belscope, I am not persuaded that its existence was part of the common general knowledge. See paragraph [94] below.

[91] In addition to the leading textbooks, with some of which all or almost all of the relevant sub-set would have some familiarity, there were review articles in prominent medical journals. I accept Dr Henderson's evidence that almost all United Kingdom consultant anaesthetists would receive monthly both the British Journal of Anaesthesia and Anaesthesia. But I was not referred to articles in those journals which discussed in any detail the rigid fibre-optic laryngoscopes mentioned in the textbooks which I mentioned in paragraph [89] above. Medical journals, which were available to some but not all of the relevant sub-set of anaesthetists, included the United States journals, namely Anesthesiology, and Anesthesia and Analgesia, and the Canadian Journal of Anaesthesia. In the latter journal in 1998 Dr E. T. Crosby and others produced a special article reviewing current literature and making recommendations on the role of newer technology in the management of an unanticipated difficult airway. Among the devices which the article recommended as alternatives to the normal direct laryngoscope when difficult intubation occurred were the Bullard laryngoscope and other rigid fibre-optic laryngoscopes. The article also recommended that clinicians should be trained in alternative methods of intubation. Again, I do not treat this article as part of the common general knowledge in the United Kingdom, not least because the journal was not widely available, but in its review of the literature it supports the conclusion that there was an awareness, at least within the relevant sub-set of the profession and probably more widely, of the existence and purpose of the Bullard laryngoscope and other rigid fibre-optic laryngoscopes.

[92] New devices were discussed at meetings of the DAS. Members attending a meeting in December 1995 discussed the Upsherscope, the Belscope and also the McCoy laryngoscope. There was evidence of the dissemination of that sort of knowledge by the better informed to others at departmental meetings and workshop meetings within hospitals. Dr Henderson spoke of informing his colleagues of the Bullard at such meetings and Dr Frerk taught his colleagues about the Belscope. In addition, morbidity and mortality meetings in hospitals involved discussion amongst anaesthetists of airways management. I accept Dr Henderson's evidence that from these various types of meeting there would have been awareness within the anaesthetist profession in the United Kingdom of rigid fibre-optic laryngoscopes, such as the Bullard, at the priority date.

[93] In the United States, as Dr Henderson pointed out, the standard textbooks, namely Roberts & Hedges' Clinical Procedures in Emergency Medicine (2^nd ed. 1998), Rosen's Emergency Medicine (4^th ed. 1998) and Tintinalli's Emergency Medicine, which the pursuer accepts were within the common general knowledge of American anaesthetists and emergency medicine practitioners, all referred to the Bullard laryngoscope. The textbook, "Manual of Emergency Airway Management", which was published in 2000 and of which Dr Walls was editor in chief, also discussed the use of the Bullard laryngoscope in its chapter on fibre-optic intubation techniques.

[94] Awareness of the existence of devices, whether through publication, specialist meetings or teaching, is one thing. But material contained in publications becomes part of the common general knowledge only if that material has been generally accepted as a good basis for further action: see paragraph [36] above. It was clear from the literature and also from Dr Henderson's evidence that an anaesthetist needed training and experience in the use of the Bullard laryngoscope as it involved a different technique of insertion down the midline of the mouth from other laryngoscopes and the position of the eye piece made its use more demanding than other devices. It is not established that either the Bullard or any other rigid fibre-optic laryngoscope was widely used or was generally seen as something which would be built on in further developments. I am satisfied, however, that the idea of indirect visualisation of the glottis by rigid fibre-optic laryngoscopes, such as the Bullard, with anatomically-shaped blades, which avoided manipulation of the head and neck, was part of the common general knowledge at the priority date. Such anatomically-shaped blades would have been within the skilled person's contemplation when alerted by an item in the prior art to the possibility of the use of a camera on a laryngoscope blade. I am not persuaded that the same is true for the Belscope. It was invented about twenty years before the priority date, in 1980. It was used predominantly as a direct laryngoscope without the prism. While the angulation of its straight portions made it potentially suitable as a platform for indirect visualisation of the glottis by a camera, there is little evidence to show any awareness among clinicians of this potential before the priority date. Indeed, Dr Walls, with all his teaching expertise in his specialised field, was not even aware of the existence of the Belscope at that time.

[95] Dr Walls gave evidence, which I generally accept, (a) that most practitioners at the priority date were content with their use of direct laryngoscopes which had a high success rate, (b) that most innovations involved modifications of direct laryngoscopes or improved training in (i) their use, (ii) the prediction of problems and (iii) the employment of rescue strategies and (c) that the use of flexible fibre-optic devices was the principal alternative method of intubation. But I also accept Dr Henderson's evidence that there was an increasing public intolerance of medical failure in the 1990s which encouraged medical practitioners to examine retrospectively adverse outcomes in morbidity and mortality meetings and to carry out training in workshops and departmental meetings. It is in this context and in the repeated references in widely-read medical textbooks, which the relevant sub-set of anaesthetists read, that the existence of anatomically-shaped rigid fibre-optic laryngoscopes, such as the Bullard, was part of the common general knowledge at the priority date. I conclude that most anaesthetists would be aware of the existence of such devices and that newly-qualified consultant anaesthetists with an interest in airways management would have a greater knowledge of them and their purpose.

[96] In relation to the medical device engineer, Mr Currie founded on the evidence of Professor Roberts that his common general knowledge would include certain textbooks, the existence and use of cameras in medical devices, where to source such cameras, the use of displays to display images from cameras, a general appreciation of optics, the use of fibre-optics in endoscopes, the use of cameras at the proximal end of fibrescopes, how to construct a sealed chamber for a camera and how to construct a sheath for a complexly-shaped laryngoscope. The medical device engineer would not be aware of, among other things, specialist books on airway management, the purpose and characteristics of intubation or the devices used to intubate, the anatomy of the mouth and throat, books on camera technology, the use of video chips at the distal end of endoscopes or the possibility of using CMOS and CCD cameras in medical applications.

[97] As I have held that the medical device engineer whom the clinician would consult at the priority date would be likely to be an experienced person working in industry rather than Professor Roberts' hospital technician (see paragraph [81] above), I consider that it is likely that his knowledge would be more extensive than that suggested by Mr Currie. I accept that he would be unlikely to know about intubation and airway management and that he would have to rely on the clinician for those matters and for the anatomy of the mouth and throat. But I think that it is likely that he or the clinician would be aware of the use of video chips at both the proximal and distal ends of endoscopes as Dr Muirhead suggested, that he would be aware of the use of CCD cameras in medical devices such as endoscopes, and that he would know how to source CMOS and CCD cameras or to consult a camera engineer for that purpose. Dr Henderson gave evidence that clinicians, including anaesthetists, were aware by the mid-1990s of the use of video chips at the distal end of endoscopes for gastrointestinal investigations. It would be surprising if a medical device engineer employed by a medical device manufacturer did not have a similar awareness of such devices and I accept Dr Muirhead's evidence on this matter.

The Pursuer's product: the Glidescope

[98] Before considering the interpretation of the Patent, it is necessary briefly to describe the product which the pursuer has marketed as it featured significantly in Dr Walls's evidence and as the defender suggested that that evidence was influenced by his experience of using the product.

[99] The Glidescope, which the pursuer sees as an embodiment of the Patent, comprises a handle, a base portion which to the eye seems curved and a lifter portion which to the eye seems substantially straight. The light source and the camera for viewing the distal part of the blade are located at the junction of the two portions. I attach as Appendix 8 a photograph of the Glidescope GVL. The pursuer also manufactures and sells a variant, known as the Glidescope Cobalt or Glidescope Ranger video baton, which comprises a handle and flexible video baton which is inserted into a transparent disposable plastic sheath. The sheath covers both the handle and the video baton and provides the blade or arm of the laryngoscope.

[100] Mr Lake submitted that the Glidescope products were irrelevant to the construction of the Patent. He submitted that they were not an embodiment of the invention claimed in the Patent for three reasons. It was necessary first to construe the Patent in order to decide whether the Glidescope was an embodiment of it. It would be circular to take the Glidescope into account when so doing. Secondly, and in any event, because the Patent claims a wide range of embodiments, the Glidescope could not be used to ascertain the limits of what was claimed. Thirdly, evidence of a patentee's subsequent conduct could not be admitted for the purpose of construing a patent: Glaverbel SA, Mummery J at p.94. I consider that there is force in Mr Lake's criticisms and, in construing the Patent, I will not have regard to the suggested embodiments as an aid to construction.

The interpretation of the Patent

[101] The pursuer in its pleadings described the invention as set out in claim 1 of the amended Patent in these terms:

"the inventive concept lies in the combination of (i) a specially-designed blade, incorporating a substantially straight, elongated distal portion arising at a distinct angle from the proximal portion, together with (ii) a video camera located on the underside of the blade or arm, and positioned well back from the distal end of the blade, just past the deflection point; and (iii) combined in a simple device which looks, and handles, like a conventional direct laryngoscope."

[102] Mr Currie relied principally on the evidence of Dr Walls to expand on this approach. Dr Walls saw the pursuer's invention, which he first encountered in the form of the Glidescope, as a novel design which incorporated a video system into a specially designed indirect laryngoscope to acquire a superior view of the larynx and vocal cords. He saw its value as greatly enhanced in that the operator could master the technique of its use quickly because it had a similar feel to a direct laryngoscope, such as a Macintosh blade, with which anaesthetists were familiar. The location of the camera and the orientation of the blade provided a broad viewing angle and gave the operator a perspective view of the glottic aperture and adjacent structures so that he could see and manipulate the endotracheal tube as it approached the vocal cords. The blade was inserted into the patient's mouth along the midline, while most direct laryngoscopic blades were inserted paraglossally. Unlike conventional direct laryngoscopes, which are lifted to improve the view of the glottis, the operator enhanced glottic exposure by tilting the Glidescope. He described his encounter with the Glidescope as "a light bulb moment" because someone had finally identified how to reduce the number of failed intubations. It was simple in appearance, lightweight and easy to use, and could be used for everyday intubations as well as to tackle difficult airways. Dr Walls explained that, while he had used the Bullard and other fibre-optic laryngoscopes, he had not thought of video laryngoscopy as a solution to the most difficult challenges of emergency airway management. Its simplicity, and the superiority of the view which it gave, resulted in rapid adoption of the Glidescope by emergency medicine practitioners in the United States. He opined that the Glidescope was a breakthrough as it gave an entirely new solution to the mystery of intubation failure.

[103] It is clear, however, that the invention and the scope of the pursuer's monopoly must be found in the words of the claims in the Patent and not in what the pursuer presents as a later embodiment of the invention. The question which I have to answer is: "what would the skilled addressee understand the patentee intended the words of his claim to mean?" I turn therefore to the construction of Claim 1 of the Patent, which I have set out in paragraph [19] above.

[104] In giving his views as to the meaning of certain integers in Claim 1 of the Patent, Dr Walls, who had been asked by the pursuer's solicitors to make certain assumptions, argued that the skilled addressee would construe them with an eye to their function, having regard to the use of the device. That use is illustrated in Figure 8 of the Patent. Thus the phrase "base portion" referred not to the part of the blade or arm between the handle and the lifter portion, but that part of the arm which was designed to traverse the mouth and oropharynx of the patient in order to place proximal end of the lifter portion, with its camera, at the posterior oropharynx of the patient. This meant that the arm of the device included a part, proximal to the base portion, which attached the arm to the handle and which would be outside the patient's mouth. This allowed the operator to manipulate the handle in front of the patient's face.

[105] Dr Walls suggested also that "substantially straight", which is used in Claim 1 to describe both the base portion and the lifter portion, should be given a functional meaning. Where the phrase was used in relation to the lifter portion, it required the portion to be sufficiently straight to provide a clear view of the glottis from the camera located proximally on its posterior surface. Excessive curvature of the lifter portion would disable the camera from providing a view of the glottis. Where used in relation to the base portion it meant sufficiently straight to traverse the oral cavity, which was an essentially straight passage. As the tongue intruded into the space of the oral cavity, it was desirable to have some curvature of the base portion to allow it to travel over the tongue more easily. Excessive curvature would prevent the base portion from traversing the oral cavity to reach the posterior oropharynx and positioning the camera, as intended, in the hypopharynx.

[106] Mr Currie submitted that the phrase "substantially straight" should be construed, first, by having regard to its normal English meaning. Further, one must read additional content from its specific use, under reference to the drawings in the Patent. And, thirdly, additional content had to be read into the phrase on the basis of how the skilled addressee would have understood it in its context in Claim 1. Thus, first, the use of "substantially" as a modifier of "straight" meant that the phrase encompassed both a geometric straight line and a range of deviations from straight. Secondly, the deviations from straight would in their context include the deviations shown in Figure 7 of the Patent. Thirdly, he submitted that the skilled addressee would give the phrase the functional meaning of which Dr Walls spoke.

[107] I recognise that the Patent introduced new terminology in its description of parts of the arm as the base portion and the lifter portion. I consider that the lifter portion was, as its name suggests, intended to be that portion of the arm which lifted the epiglottis. Strictly speaking, either the whole laryngoscope from the handle to the tip or only the tip, which was placed against the posterior of the epiglottis or in the vallecula, effected the lifting. Thus the lifter portion is that portion of the arm of the device which includes the part which makes contact with the patient's tissue at or near the epiglottis where pressure is applied to expose the glottis. That functional meaning arises from the use of the word "lifter".

[108] But I am not persuaded that it is appropriate to give the other integers of Claim 1 of the Patent the functional meanings for which Mr Currie argued. I have reached this view for the following reasons.

[109] First, in the pre-characterising part of Claim 1, the patentee has chosen to describe the device as comprising an instrument with two substantially straight elongate portions with defined lengths and at a defined angle, and with a viewer operably secured to the posterior side substantially where the two portions meet. In the characterising part of the Claim it is stated (a) that the defined length of the lifter portion is about as long as the defined length of the base portion and (b) that the camera viewer is directed toward the distal end of the lifter portion. The emphasis throughout the claim is on the geometry of the device and there is no mention of function other than the reference to the lifter portion.

[110] Secondly, as Mr Lake submitted, the patent envisages that the defined angle (which is shown as (208) in Figure 7 of the Patent) could range from 5º to 85º. Thus the invention covers a range of devices in which the combination of the base portion and the lifter portion could vary from being almost a straight line to being almost a right angle. The devices would require, in accordance with the characterising part of Claim 1, to have an approximation in the defined lengths of the base portion and the lifter portion but the way in which a particular device could function would differ markedly depending upon its configuration. The Patent acknowledges in paragraph 48 that the overall geometry between the base portion and the lifter portion is important for the effective operation of the instrument; but it also claims that the invention encompasses this wide range of angles. I recognise, of course, that the preferred embodiment illustrated in Figure 7 of the Patent had an angle (208) of 45º, and would very probably be used only for indirect visualisation of the glottis, as Dr Walls suggested. But the scope of Claim 1, encompassing as it does Claim 11, is much wider.

[111] Nowhere in the patent is it stated that the invention is of a device to be used exclusively for indirect laryngoscopy. Dr Walls's perception of the invention as a laryngoscope solely for indirect visualisation, which he derived from his experience with the Glidescope, did not take adequate account of the range of sizes and angles claimed within the Patent. If the defined angle were to be 5º, the laryngoscope would be used like a straight blade. The clinician would insert the blade into the patient's mouth paraglossally and have to move the tongue aside. He would also be likely to have to place the patient's head in the sniffing position. Further, the Patent gave no support for the submission, which was not otherwise backed up by evidence, that straighter blades were to be used on paediatric patients to obtain such indirect visualisation. Paragraph 48 of the Patent referred only to the use of proportionately smaller sizes in paediatric applications. It is only by ignoring the level of generality of the Patent's claims that one can erect an interpretation based on the functioning of an indirect laryngoscope. That interpretation does not work when regard is had to the generality of the wording of the claims.

[112] Thirdly, Mr Currie's construction of the expression "substantially straight" involves giving meaning to the word "straight" and also to the word "substantially" as a modifier or extender of "straight", consistently with figure 7 of the Patent, before further extending the meaning by reference to this functional approach. This involves a departure from the normal use of words. But, as Lord Hoffmann stated in Kirin-Amgen at paragraph 34, one would not expect a patentee to depart from the conventional use of language very often. I am not persuaded that the patentee intended to do so in this case.

[113] Fourthly, each of the terms "substantially straight", "base portion" and "lifter portion" were not terms of art. If the patentee had intended that they were each to have a functional meaning, one would have expected him to say so. Thus, if the "base portion" were intended to refer to the part of the arm which traversed the patient's mouth rather than, as the defenders contend, the part of the arm between the distal surface of the handle and the proximal end of the lifter portion, one might have expected some statement of this function. Yet there is none. There is no mention of a third part of the arm, proximal to the base portion. The statement in paragraph 47 of the Patent that the arm "includes" a base portion and a lifter portion does not support the existence of a third part of the arm as the sentence goes on to refer to the portions being best shown in Figure 7. The extent of the arm which traversed the mouth would vary from patient to patient and would also depend upon whether the arm was inserted into the patient's mouth on the midline or paraglossally, unless in every case the clinician moved the instrument from the paraglossal to the midline position. I am also not persuaded by the suggestion that one can infer from Claim 2 that Claim 1 envisaged a third part of the arm. Claim 2 is in the following terms:

"The intubation instrument of claim 1, wherein said elongate arm (22) has a midpoint (302), and said elongate base portion (202) meets said elongate lifter portion (204) substantially near said midpoint (302)."

Claim 1 referred in the characterising part to the two portions as being "about as long as each other". There is no requirement that a dependent claim be narrower than Claim 1. The difference in wording of the two claims is not a sufficient foundation in which to place the edifice which the pursuer sought to erect.

[114] Similarly, there is nothing in the Patent to support the view that the expression, "substantially straight" has a functional meaning which extends its natural meaning to cover any configuration of the base portion, including a distinct curve, so long as the operator without difficulty can place the camera in the oropharynx with a view towards the glottis and the distal tip of the arm in a position to lift the epiglottis. The skilled addressee at the priority date would have been well aware of the existence of curved blades and straight blades, including straight blades which had some limited curvature over part of their length, particularly at or close to the distal tip. He would have no reason to give an extended functional meaning to "substantially straight".

[115] Fifthly, the drawings, including Figures 7 and 8, do not support the functional interpretation of either "base portion" or "substantially straight". Once the representation of the curved endotracheal tube has been identified and discounted, Figure 7 depicts the base portion (202) as completely straight or, on the anterior surface, as deviating from straight only at its proximal and distal ends. If the preferred embodiment had involved a curved base portion, as in the Glidescope, one would have expected the Patent to disclose that. On the pursuer's approach, figure 7 is not illustrating what Lord Hoffmann in Improver Corporation described as "the most perfect, best known or striking example of the class." See paragraph [29] above. Further, the "defined angle" (208) is depicted as being the angle from the horizontal plane of a straight base portion to the plane of a straight lifter portion, supporting the idea that the patent was describing, in accordance with ordinary usage, two substantially straight portions joined at a defined angle. Figure 7 also shows the length of the base portion on the posterior surface (202) as being from the handle to the proximal end of the lifter portion.

[116] Sixthly, while it is possible that the patentee could have used the expression "substantially straight" in different senses in relation to the lifter portion and the base portion, one would not expect him to do so. Yet on a functional approach the expression would allow very limited deviation from straight in relation to the lifter portion while encompassing much greater curvature in relation to the base portion. This consideration, while not of great weight as I am enjoined to eschew meticulous verbal analysis, supports the view that the skilled addressee would not understand the patentee to be using the expression in a functional sense.

[117] Seventhly, there would have been no need to use the expression "substantially straight" if the expressions "base portion" and "lifter portion" had the functional meanings for which Mr Currie contended. This supports the view that they did not and that the use of the expression "substantially straight" was a deliberate limitation of the claim. I am reminded, by way of analogy, of the statement of Hoffmann LJ in Société Technique de Pulverisation STEP v Emson Europe Ltd [1993] RPC 513 (at p.522):

"The well known principle that patent claims are given a purposive construction does not mean that an integer can be treated as struck out if it does not appear to make any difference to the inventive concept. It may have some other purpose buried in the prior art and even if this is not discernible, the patentee may have had some reason of his own for introducing it."

[118] Eighthly, as both the patentee and the skilled addressee are taken to have some knowledge of the basic principles of patentability, regard must be had to the prior art of which they are treated as having knowledge. In the light of the Wood patent (see paragraphs [66] and [67] above) the description of two "substantially straight" portions of about equal length and the requirement of a defined angle between them appear to be a deliberate delimitation of the scope of the invention. This suggests a narrower construction than that for which Mr Currie argued. I am satisfied that the Wood patent was not part of the common general knowledge. But it was referred to in the Patent. To my mind the relevant general principle is that the court should not construe the Patent in a way which leads to the result that the prior art referred to in the specification destroys the novelty of the claims. In Beloit Technologies Inc. [1995] RPC 705, Jacob J (at p.720) stated:

"I believe Article 69 of the EPC does not legitimately allow courts to construe claims using the prior art either to widen them or narrow them. There is normally no reason to suppose the patentee when he set the limits of his monopoly knew of a particular piece of prior art which is therefore irrelevant in deciding what those limits are. Of course the position is different if the prior art is specifically acknowledged in the patent. The purposive construction would lead to a construction of the claim which did not cover that acknowledged prior art: it can hardly have been the inventor's purpose to cover that which he recognises was old."

Similarly, in Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd [2010] RPC 8, Jacob LJ (at paragraph 21) stated:

"Even without a two-part claim structure, because the skilled reader knows that the patentee is trying to claim something which he, the patentee, considers to be new, he will be strongly averse to ascribe to the claim a meaning which covers that which the patentee acknowledges is old. And if the patentee not only acknowledges that a particular piece of prior art is old but then has a pre-characterising clause which is fairly obviously based on it, the skilled reader will be even more strongly inclined to read that clause as intended to describe that old art."

This exclusion of what the patentee acknowledges as old does not mean that

the skilled addressee is taken to have read every prior patent to which the specification of the patent in suit refers. But where the specification identifies problems in the prior art by reference to particular patents and states that the invention solves those problems, it is legitimate to look at the earlier patents to understand what the patentee is saying. See, for example, Abbott Laboratories Ltd v Medinol Ltd [2010] EWHC 2865 (Pat). See also Stamicarbon/Activated Support (Case T 288/84) [1986] EPOR 217 in which the EPO Technical Board of Appeal held that it was proper to look at the cited prior art, which the patent claimed to have developed further, in the context of a challenge to the sufficiency of the disclosure. Similarly, if, in a European Patent, it is apparent from the specification that the pre-characterising part of the claim is based on a particular item of prior art, the court can look at that prior art in interpreting the pre-characterising part of the claim. See, for example, Boegli-Gravures SA v Darsail-ASP Ltd [2009] EWHC 2690 (Pat). It is, however, important to bear in mind that there is always the possibility that the specification may show, through an incorrect summary of the relevant prior art, that the patentee has misread an earlier patent. In such a case it is the patentee's understanding of the prior art rather than the terms of the earlier patent which will be relevant to the construction of the patent in suit.

[119] I do not detect any misunderstanding of the Wood patent in the specification of the Patent. It described a video laryngoscope and taught the use of a video camera on the posterior side of the blade to provide video imaging of a patient's airway passage during use of the laryngoscope. In the embodiment which allowed the camera to be moved on a track when the laryngoscope was in use, the drawings illustrated the track on a curved blade. But the text also provided that the track could be situated at an elbow between an elongated straight proximal portion of the blade and a distal section. The illustration in Figure 2 was of a long straight proximal portion, a small elbow and a short, gently curved distal section close to the tip of the blade. As so illustrated, the device would, as the Patent stated in paragraph 9, "require undesirable manipulation of the patient's head and neck."

[120] Nonetheless, the citation of the Wood patent points towards the use in the Patent of expressions such as "substantially straight" as deliberately chosen words of limitation. If the expressions, "base portion", "lifter portion" and "substantially straight" were to be given the functional meanings for which the pursuer contended, that would allow each portion of the blade to be ever so curved provided only that the blade could still traverse the oral cavity, place the tip at or near the epiglottis and allow visualisation of the glottis via the camera located substantially where the two portions, which were of about equal length, met. If that were correct, the validity of the Patent would be seriously in doubt.

[121] The Wood patent taught the use of a camera as the viewer. The camera was located on the posterior side of laryngoscope blade and was positioned or could be manoeuvred to get a view of the glottic aperture. As I discuss in more detail below when I consider the validity of the Patent, locating the camera in a fixed and optimal position on a blade which was substantially curved would have risked a challenge for obviousness: see paragraphs [153]-[160] below. The patentee's awareness of the Wood patent supports the view that what the Patent presented as novel was the particular geometric shape of the arm or blade and the position of the camera thereon.

[122] In reaching this view I have taken the skilled addressee's knowledge of prior art within the common general knowledge to include an awareness of the existence of rigid fibre-optic laryngoscopes, such as the Bullard, which had a shape which was compatible with the relevant human anatomy without manipulation of the head and neck. That common general knowledge would not extend to a working knowledge of the use of such devices. But awareness of the existence of anatomically-shaped blades is not critical to my conclusions on construction of the Patent; it has more bearing on issues of validity. The skilled addressee in reading the Patent would also be aware of the use of a camera on the Berall laryngoscope, as the Patent referred to it in paragraph 8: see paragraph [65] above.

[123] In summary, the skilled addressee in construing the Patent cannot, without a good reason, ignore "substantially straight". Equally, he cannot ignore the range of geometric configurations of the device which the Patent encompasses within the invention and which undermine both the idea that the device was to be used only for indirect visualisation of the glottis and the functional interpretation in relation to the expressions "substantially straight" and "base portion". The pursuer's approach to construction, which rested on the evidence of Dr Walls, and the assumptions which its solicitors gave him, about a functional interpretation of the expressions which were in dispute, failed to take account of the range of geometric configurations of which the patentee claimed his monopoly.

[124] In so concluding, I have not ignored the evidence of Dr Walls and Professor Roberts that it is possible to ascertain a "defined angle" as required by the Patent even if one were to take the functional interpretation of the "base portion" which the pursuer urged and if that portion were curved. In their evidence that exercise involved either (i) taking the angle between the perpendicular of the plane of the handle and the plane of the lifter portion or (ii) identifying the plane of a curved base portion and taking the angle from that plane to the plane of the lifter portion. But I am not persuaded that that is what the patentee had in mind when he spoke of the "defined angle" in Claims 1 and 11-13 and illustrated it in figure 7 of the Patent as the angle between the plane of a straight base portion and the plane of the straight lifter portion.

[125] The parties also did not agree on the meaning of the expression "a viewer operably secured to said posterior side" of the elongate arm in Claim 1. I am not persuaded that Mr Lake is correct to contend that the expression requires that the camera be secured to the posterior external surface of the arm. The expression could bear that meaning and I note that paragraph 49 of the Patent describes the camera as being "operably secured to the instrument, ...positioned along the posterior surface of the lifter portion 204". But to my mind Mr Lake's interpretation involves too narrow a reading of the expression in the claim, which differs from paragraph 49 and which can also mean that the camera is located securely within the posterior side of the arm, as illustrated in figure 7. Paragraph 53 of the Patent speaks of the camera being preferably secured "within a sealed chamber 224 within the arm 22". Similarly, the expression is habile to include the situation in which the camera is located at the end of a camera stick (which also contains a light source) and within a sheath which provides the lifter portion of the arm and covers the proximal part of the arm thus created, if such a device were within the scope of the Patent.

[126] I do not think that the "Protocol questions" in Improver Corporation (see paragraph [29] above) provide much assistance in this case. They confirm the need for a purposive approach, which I have sought to adopt. I do not consider that the Patent is using figurative language when it speaks of "substantially straight". But the use of that expression in context and the cited prior art suggest, as I have said, a deliberate restriction of the claimed scope of the invention. I observe that in Catnic strict verticality was the ideal embodiment of the invention. By contrast, in this case, if the pursuers' interpretation were correct, the ideal embodiment would involve a base portion with significant curvature to assist mid-line insertion of the blade as distinct from the straight or substantially straight base portion which figure 7 illustrates.

[127] If one were to address the Improver questions, I can see that an ability to extend the proximal portion of the arm, which the defender's product has, might not take an allegedly infringing product outside the scope of the Patent. But I am persuaded that the relative straightness or curvature of the base or proximal portion would have a material effect on the way the invention works as, depending on the angulation of the portions, it would affect the ease with which and the manner in which the arm was inserted into the patient's mouth.

The validity of the Patent

(i) The statutory provisions

[128] The defender challenges the validity of the Patent under section 72 of the 1977 Act which provides that:

"Subject to the following provisions of this Act, the court ... may by order revoke a patent for an invention on the application of any person (including the proprietor of the patent) on (but only on) any of the following grounds, that is to say -

(a)   the invention is not a patentable invention; ..."

This power to revoke a patent for an invention which is not a patentable invention extends to a European Patent: section 77. An invention is patentable in accordance with section 1 of the 1977 Act, so far as is relevant in this case, if (a) the invention is new and (b) it involves an inventive step. Section 2 provides:

"(1) An invention shall be taken to be new if it does not form part of the state of the art.

(2) The state of the art in the case of an invention shall be taken to comprise all matter (whether a product, a process, information about either, or anything else) which has at any time before the priority date of that invention been made available to the public (whether in the United Kingdom or elsewhere) by written or oral description, by use or in any other way ....."

Section 3 provides:

"An invention shall be taken to involve an inventive step if it is not obvious to a person skilled in the art, having regard to any matter which forms part of the state of the art by virtue only of section 2(2) above...."

[129] The defender in its counterclaim for revocation has pleaded both anticipation (statement 18) and obviousness (statement 19). The onus rests on it to prove lack of novelty or obviousness. In the event, while the defender cited several examples of prior art which it submitted gave rise to an obviousness challenge, it confined its challenge based on anticipation to only two prior patents, namely the Wood and Moritex patents.

(ii) Anticipation

[130] The notion behind anticipation is that it would be wrong to enable a patentee to prevent a man from doing what he has lawfully done before the patent was granted: Windsurfing International Inc. v Tabur Marine (Great Britain) Ltd (supra), Oliver LJ at p.77.

[131] A challenge to validity based on anticipation requires the court to address two concepts, namely, prior disclosure and enablement. In Arrow Generics Ltd v Akzo NV 2008 SC 518, the Lord President (Lord Hamilton) at paragraph 104 stated:

"A party seeking revocation of a patent on the ground that it has been anticipated by the prior art has to satisfy the court on two points, namely, whether the prior art disclosed the invention which had been patented ('disclosure') and whether the ordinary skilled man would be able to perform the disclosed invention if he attempted to do so using the disclosed matter and common general knowledge ('enablement') (see SmithKline Beecham, per Lord Hoffmann, para 14)."

The reference is to SmithKline Beecham PLC's (Paroxetine Methanesulfonate) Patent [2006] RPC 10. Thus, when assessing disclosure in the context of an assertion of anticipation by prior publication, one must compare the earlier publication with the patentee's claim, construing each at the date of its own publication and disregarding subsequent events. In General Tire & Rubber Co Ltd (supra), Sachs LJ stated (at pp.485-486):

"If the earlier publication, so construed, discloses the same device as the device which the patentee by his claim, so construed, asserts that he has invented, the patentee's claim is anticipated, but not otherwise. .... To anticipate the patentee's claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented. ... A signpost, however clear, upon the road to the patentee's invention will not suffice. The prior inventor must clearly be shown to have planted his flag at the precise destination before the patentee."

Thus, as summarised by Lord Hoffmann in SmithKline Beecham (at paragraph 22):

"The matter relied upon as prior art must disclose subject-matter which, if performed, would necessarily result in an infringement of the patent."

[132] Lord Hoffmann went on (in paragraph 26) to describe the separate concept of enablement as meaning that the ordinary skilled person would have been able to perform the invention which satisfies the requirement of disclosure. He equated the test of enablement of a prior disclosure for the purpose of anticipation with the test of enablement of the patent in suit for the purpose of sufficiency (paragraph 27). Once it has been established that there has been disclosure and the question is whether the subject-matter of the invention has been enabled, the skilled person is assumed to be willing to make trial and error experiments to get it to work (paragraph 30).

(iii) Obviousness

[133] The philosophy behind obviousness is that a patent is granted only for an invention and that which is obvious is not inventive. It would be wrong to prevent a man from doing something which is merely an obvious extension of what he had been doing or of what was known in the art before the priority date of the patent in suit: Windsurfing (supra), Oliver LJ at p.77.

[134] The courts in the United Kingdom have generally adopted a structured approach to the analysis of a challenge to the validity of a patent based on an allegation of obviousness. Case law has recognised four steps in this process. The first three orientate the tribunal before it tackles the fourth step, which has been described as "the key, statutory step": Actavis UK Ltd v Novartis AG [2010] FSR 18, Jacob LJ at paragraph 21. Those four steps, which originated in Windsurfing, are as follows:

(1) identify the notional skilled person and what was the relevant common general knowledge in the art at the priority date;

(2) identify the inventive concept embodied in the claim in question or, if that cannot readily be done, construe the claim; (It may not be appropriate in all circumstances to attempt to identify the inventive concept as, for example, when there is an involved dispute as to what that concept is. The court will wish to avoid a prolonged satellite debate.)

(3) identify the differences, if any, between matter forming part of the state of the art and the alleged invention; and

(4) assuming no knowledge of the alleged invention, decide whether the steps to reach the alleged invention were (technically and practically) obvious or required any degree of invention. (The skilled person is not allowed to look with the benefit of hindsight at what is known once the alleged invention is known. Commercial obviousness is not a relevant consideration.)

See Windsurfing, Oliver LJ at pp.71 and 73-74; Pozzoli SPA v BDMO SA [2007] FSR 37, Jacob LJ at paragraph 23; Actavis, Jacob LJ at paragraphs 18-21; and SABAF SpA v MFI Furniture Centres Ltd [2005] RPC 10, Lord Hoffmann at paragraphs 20-27.

[135] It is necessary to say more about the "inventive concept" as it was a matter of dispute in this case. It has been described as "making a précis" by stripping out unnecessary verbiage (Pozzoli paragraph 18) and as "the essence of what is in the claim" (Pozzoli paragraph 29). But making such a précis to identify the essence of the claim is not helpful if there is a significant dispute over the précis; it distracts from the words of the claim: Actavis, Jacob LJ at paragraph 19. Further, by way of analogy, in Conor Medsystems Inc. v Angiotech Pharmaceuticals Inc. [2008] RPC 28, Lord Hoffmann warned against watering down the claimed invention and stated at paragraph 19:

"In my opinion, however, the invention is the product specified in a claim and the patentee is entitled to have the question of obviousness determined by reference to his claim and not to some vague paraphrase based on the extent of his disclosure in the description."

While the circumstances of the Conor case were quite different from those of the present case, Lord Hoffmann's emphasis on referring to the patentee's claim underlines the importance of the "inventive concept" being an accurate précis, if it is to be used effectively in assessing the question of obviousness. If it is not accurate, the court in determining obviousness should focus on the words of the claim.

(iv) Applying the law in this case

[136] I deal with the question of anticipation below when I discuss the matters in the prior art which are said to be prior disclosure. I have sought to identify the skilled person in paragraphs [72]-[83] above. I have also discussed the common general knowledge in paragraphs [84]-[97]. When considering the test of obviousness, the skilled person has to take account of the prior art in the context of the common general knowledge.

[137] As I have said (in paragraph [101] above) the pursuer asserts that the inventive concept in Claim 1 of the Patent is as follows (Closed Record p.8 and written submission, paragraph 8.12):

"The inventive concept of Claim 1 of the Patent lies in the combination of (i) a specially-designed blade or arm, incorporating a substantially straight, elongated distal portion arising at a distinct angle from the proximal portion, together with (ii) a viewer/video camera located on the underside of the blade or arm, and positioned well back from the distal end of the blade, just past the deflection point; and (iii) combined in a simple device which looks, and handles, like a conventional direct laryngoscope."

[138] It is clear from, amongst others, the decision of the First Division in Arrow Generics Ltd that the court when using the technique of the inventive concept must identify the inventive concept in relation to each claim distinctly. In this case, however, Mr Currie submitted that the same inventive concept ran through the dependent claims (written submission, paragraph 8.17). Further, the pursuer conceded in Answer 4 to the Counterclaim that if claim 1 were invalid for lack of inventive step, claims 2-10, 14-16 and 19 of the proposed amended Patent would also be invalid. That would leave for consideration only claims 11-13, in which the angles between the base portion and the lifter portion are specified, and proposed claim 18, in which the transparent protective sheath is positioned over the instrument. They do not require a précis and I consider them in paragraphs [172] and [187]-[200] below.

[139] The pursuer's description of the inventive concept was supported by Dr Walls's evidence which was based on his experience of using the Glidescope. I have discussed his evidence in paragraph [102] above, but will summarise it again so far as it is directed to this question. He spoke of the Glidescope as being a laryngoscope designed specifically for indirect visualisation of the glottis and not an adaptation of a conventional laryngoscope which sought to create a direct line of sight. It comprised a two-part blade, which bypassed the tongue rather than, as with prior art, being used to move the tongue aside on insertion into the mouth. The Glidescope and the Patent also taught that the camera should be located significantly proximal to the position of the viewer in the existing art. By positioning the camera back from the tip of the lifter portion the device gave the clinician a perspective view of the glottis which allowed him to observe the endotracheal tube approach the glottic aperture. Dr Walls considered that using the Glidescope felt similar to using a traditional laryngoscope such as the Macintosh. The clinician, when using the Glidescope, had merely to tilt the instrument to view the glottis, unlike the conventional direct laryngoscope blade which had to be lifted to obtain the desired view.

[140] I accept that Dr Walls was being truthful and straightforward in describing his perception of, and experience in using, the Glidescope. But I do not consider his evidence to be a basis for accepting as useful the pursuer's definition of the inventive concept. The definition is not helpful as a précis because it omits important integers in Claim 1. There is no mention of the substantially straight base portion. There is no mention of the important statement in the characterising part that the base portion and the lifter portion were of about the same length. It is to my mind strange that a précis should overlook something stated in a short characterising part. It also makes a claim for ease of handling which is not part of Claim 1 and is, in any event, inconsistent with the generality of the claimed invention, specifically in the range of angles claimed in Claim 11 which would significantly affect the way in which the invention could be used.

[141] I therefore approach obviousness by construing the relevant claims. I have discussed the construction of the patent in paragraphs [101]-[127] above and deal with the allegedly independently valid claims separately below. But, in assessing obviousness against the prior art on which the defenders ultimately relied, I also comment briefly on what my views would have been if I had accepted the more general inventive concept which the pursuers proponed and had construed the Patent as Mr Currie invited me to.

[142] Before doing so, I comment briefly of step 4 of the Windsurfing approach as clarified in the later case law. The statutory test of obviousness is multifactorial and the factors which are relevant may vary from case to case: Actavis, Jacob LJ at paragraph 26. In that case the court identified a number of possible factors. First, the court could consider whether the prior art made it obvious to try if there was a fair expectation of success: Conor Medsystems Inc, Lord Hoffmann at paragraph 42. Secondly, in some cases it is appropriate to use the "problem and solution approach" which the European Patent Office uses in its assessments. This involves (i) identifying the closest prior art, (ii) establishing the objective technical problem to be solved and then (iii) considering whether the claimed invention would have been obvious to the skilled person. This approach is not useful when invention is in perceiving the problem: Actavis, Jacob LJ at paragraph 25. But in this case the problem was known well before the priority date. Thirdly, the commercial success of an embodiment of the invention may be a pointer to its inventiveness, especially if there was a long-felt want. Fourthly, the court should also consider other factors such as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort in pursuing them and the expectation of success: Generics (UK) Ltd v H Lundbeck A/S [2007] RPC 32, Kitchin J at paragraph 72; Conor Medsystems Inc, Lord Hoffmann at paragraph 42.

[143] In this case the parties were in agreement that the problem which the Patent sought to address was how to intubate successfully without having to manipulate the patient's head and neck, particularly if the patient had suffered injuries to those parts of his body: see paragraph 7 of the Patent. Traditional methods of intubation enjoyed a high percentage rate of success but the consequences of failed intubation were potentially fatal. While most anaesthetists may have been satisfied with the equipment which was available and which had a low failure rate, I accept Dr Henderson's evidence that many were concerned to reduce the failure rate and that that concern contributed to the formation of the DAS in the United Kingdom and similar bodies in other countries. Further training in the use of direct laryngoscopes, in fibre-optic laryngoscopes, and in the management of emergencies was the principal focus of the attempts to reduce the number of failed intubations. Those with a special interest in airway management also taught the use of other equipment such as rigid fibre-optic laryngoscopes. But those laryngoscopes, such as the Bullard, had only limited commercial success for various reasons which Dr Henderson discussed in his evidence. By contrast, Dr Walls described the rapid uptake of the Glidescope in the United States of America. While the pursuer did not lead detailed evidence on the extent of the commercial success of its product, it was clear from Dr Walls's evidence that the Glidescope had been significantly successful in the market.

[144] I now turn to the prior art on which the defender founded. In his closing submission Mr Lake narrowed considerably the basis of his attack on the Patent and did not cite prior art which had been addressed in the written pleadings and had been the subject of dispute in the evidence. Mr Currie in response invited me to question the authority of Dr Henderson's evidence on the basis that the defender had not relied on some of his assertions as to anticipation or obviousness in relation to the prior art. I am not satisfied that I should draw that conclusion from Mr Lake's decision to concentrate on a limited number of items in the prior art. Mr Lake submitted that he was focusing in his submissions on the principal challenges rather than exhaustively discussing each item in the prior art. I see no reason to doubt that assertion.

(a) The Bellhouse patent and the Belscope

[145] The first item in the prior art which I have to consider is the Belscope: see paragraphs [59]-[61] above. Dr Henderson's initial report had argued that the Belscope had anticipated the unamended Claim 1, but after he wrote that report the claim was amended by the European Patent Office. The defender did not assert that the Bellhouse patent or the Belscope anticipated amended Claim 1 of the Patent, which introduced in its characterising part the camera as the viewer. I therefore have to consider only the obviousness challenge. I am not persuaded that the Belscope made obvious the alleged invention in the Patent. The Belscope was not widely used although Dr Frerk, unusually, taught his trainees how to use it. It was not disputed and the literature supported the view that it was usually used as a direct laryngoscope, creating a direct line of sight. See paragraph [61] above. Clinicians only rarely used the prism to obtain an indirect view of the epiglottis and the glottic aperture. Neither the Bellhouse patent nor the Belscope taught the creation of a device to be used predominantly for indirect visualisation of the glottis, which the Patent taught in its preferred embodiment. While it was an angulated straight bladed laryngoscope, the clinician used it differently from the laryngoscope described in the Patent. The Belscope was inserted along the right paraglossal gutter of the patient's mouth and remained in use in the right hand side of the mouth while the Patent allowed for midline insertion over the dorsum of the patient's tongue.

[146] In this regard I accept the evidence of Dr Walls and Dr Frerk that the Belscope was seen essentially as a direct laryngoscope with the capacity for indirect visualisation by bending the line of sight through use of the prism. It did not involve the use of camera; nor was it obvious to replace the prism with a camera. The prism was difficult to use and gave a narrow field of view which could be disorienting to the clinician. While the angle between the straight portions of the blade resembled the angle of the preferred embodiment of the Patent (see paragraph [59] above), the distal portion of the blade of the Belscope was sufficiently long to traverse the mouth and oropharynx and place its tip at or near the epiglottis. The proximal part of the blade was at an angle principally to avoid damaging the patient's upper teeth when using the laryngoscope to lift the epiglottis. In use that part of the blade was in large measure outside the patient's mouth. It was not obvious to fit a camera onto this blade to avoid manipulation of head. Thus, whether one construes the Patent as I have or in the way the pursuer urges, the Belscope does not support the defender's challenge to validity on the ground of obviousness.

(b) The Bullard Patents and Laryngoscope

[147] I have described the Bullard patents and the Bullard laryngoscope in paragraphs [55] and [56] above. The defender did not assert that either the patents or the laryngoscope anticipated the patent in suit.

[148] Dr Henderson described the Bullard laryngoscope as the first curved rigid indirect laryngoscope. He described it as the most important advance in intubation since the introduction of the flexible fibre-optic laryngoscope. It was designed to avoid having to manipulate the head and neck. The clinician could insert its anatomically-shaped blade by rotating it into the mouth and the pharynx along the midline. It was not necessary to displace the tongue laterally. The proximal part of the Bullard laryngoscope was curved as was the distal part which was located in the pharynx; but the distal end of the distal part beyond the lens was substantially straight to allow visualisation of the glottis. In the mid 1990s a camera was attached to the proximal eyepiece as a teaching aid to display what the clinician would see on using the eyepiece. This was reported by E T Crosby in an article, "Techniques using the Bullard laryngoscope" in Anesthesia and Analgesia 1995; 81: 1314-5; but it was not suggested that that article was in the common general knowledge.

[149] The Patent differed from the Bullard laryngoscope and the Bullard patents in its use of the video camera, and in its location of the camera at the junction between the base portion and the lifter portion, giving a perspective view of the glottic aperture, and on my construction in its geometric shape. Both Dr Walls and Dr Frerk spoke of the limited availability and use of the Bullard device at the priority date. Dr Walls explained that the Bullard and other rigid fibre-optic laryngoscopes addressed the difficulties which clinicians encountered in using a flexible fibre-optic laryngoscope on a supine patient. He stated that the Bullard differed from direct laryngoscopes in its shape and in its manner of use as the clinician had to place his eye on the eyepiece when using the laryngoscope. Dr Walls also explained that the fibre-optic lens was positioned to give a close up view of the relevant tissue and not the panoramic view which the Patent taught. He explained that even after the commercial embodiment of the Bullard invention placed the fibre-optic viewer further back from the distal tip than the first patent described, it still provided a narrow view in comparison with the Patent.

[150] In my opinion it was not obvious to use the Bullard as a starting point to create a new video laryngoscope at the priority date. The limited availability and use of the device militated against that role. I note also that, as Mr Currie emphasised in his submission, Dr Henderson stated that in 1997 he considered that the Bullard performed satisfactorily in situations in which an indirect view of the glottis was required. In my view, something else in the prior art would have had to have prompted the idea of using a camera as a viewer on a laryngoscope blade.

[151] On my construction of the Patent, the Bullard patents and laryngoscope did not make the alleged invention obvious as the geometric shape of the blade was radically different from them. Even if one were to adopt the pursuer's construction, I do not think that it would have been an obvious step to place a camera in the middle of the curved part of the Bullard blade. Accordingly, the obviousness challenge based on the Bullard patents and laryngoscope fails.

[152] The significance of the Bullard laryngoscope and the other anatomically-shaped rigid laryngoscope blades in this context, however, lies in the awareness in the common general knowledge of blades with such shapes. I discuss this further in paragraphs [158], [165], [171] and [172] below.

(c) The Wood patent

[153] I described the Wood patent in paragraphs [66] - [68] above. The defender submits that this device anticipated the Patent and in any event rendered it obvious.

[154] The defender's case of anticipation arises only if the pursuer's construction of the patent were to be adopted. In particular, the pursuer's submission that the base portion can be curved to any degree which allows the blade to traverse the oral cavity and its implicit airbrushing out of the characterising feature that the base portion and the lifter portion are of about the same length meant that the Wood patent anticipated Claim 1 of the Patent.

[155] In arguing that the Wood patent did not anticipate Claim 1 of the Patent Dr Walls relied essentially on only two integers in Claim 1, namely (i) that the lifter portion was elongate and (ii) that the lifter portion and base portion were of substantially the same length. In relation to the first suggested distinction it appears to me that, while the Wood patent does not teach any particular shape of blade, the embodiment of the invention on an essentially straight blade in figure 2 of the Wood patent shows an elongate part of the blade which would serve the purpose of the lifter portion. There is more force in the second suggested distinction, although I observe that that suggestion is not expressly encompassed within the inventive concept on which the pursuer relies. On the pursuer's interpretation of the Patent, both the base portion and the lifter portion could be curved and one could embody the invention with a lower defined angle than that of the preferred embodiment. In the curved blade embodiment of the Wood patent in figure 4 it would be hard to discern the precise point at which the blade ceased to be a base portion and became a lifter portion if one were to give functional meanings to those terms.

[156] If I had accepted the pursuer's interpretation of the Patent but also had regard to the range of angles which the Patent permits, I would not have concluded that the Wood patent anticipated the Patent. I consider that the Wood Patent did not plant its flag at the precise destination as it did not teach the placing of the camera in a fixed position well back from the distal end of the blade, a position which, as Dr Walls stressed, gave rise in the Glidescope to a perspective view of the glottis. In any event, as my construction of the Patent rejects the functional approach which the pursuer urged and focuses on the geometric descriptions in Claim 1, I am satisfied that the anticipation challenge fails.

[157] If I am wrong in my view on the anticipation challenge on the pursuer's interpretation of the Patent, I am satisfied that that construction would expose the Patent to a challenge on the ground of obviousness, particularly when one takes into account the degree of curvature which the functional construction allows and range of angles covered by the Patent.

[158] It seems to me that the skilled person would see that the Wood patent envisaged both a fixed camera and a moveable camera and would learn that the latter could be moved in use to get a preferred view. The Wood patent itself, in its moveable camera embodiment, taught that one should look for a preferred view. The skilled person would readily appreciate that one could fix the camera at different positions on a curved blade and that one could limit the curve which was distal of the camera lens to enable a clear view of the larynx or glottic aperture. In seeking an appropriate view the skilled person by trial and error could readily settle on locating the camera at or close to the midpoint of the generally curved blade with a much reduced curve distal to the lens. Being aware of the existence of anatomically-shaped blades, such as the Bullard, as part of the common general knowledge, the skilled person would readily produce by trial and error a blade which would fall within the terms of the Patent as interpreted by the pursuer, including the positioning of the camera to give a perspective view. Mr Lake also referred to Hallen Co. v Brabantia (UK) Ltd [1991] RPC 195 (Slade LJ at p.216) and Hoechst Celanese Corporation v BP Chemicals Ltd [1997] FSR 547 (Laddie J at pp. 573-574) in support of a submission that obtaining a perspective view was, as a matter of generality, an added or unexpected benefit which would not found a patent if it were obvious to put a camera on the blade. I do not accept that submission. But the Wood patent taught the skilled person to look for a preferred view and that teaching could be applied to other laryngoscope blades when the skilled person attached cameras to them.

[159] Dr Walls pointed out differences which he saw between the Wood patent and the Glidescope such as (i) the blade designed to house, protect and optimally place the camera, (ii) the specially-designed angulation to create the perspective view of the glottis, and (iii) the use of the Glidescope only for indirect laryngoscopy. But in relation to (i) I see the Wood patent as having a blade designed to protect and teaching the clinician to achieve an optimal placing of the camera. In relation to (ii) and (iii) Dr Walls's observations are valid only in the preferred embodiment of the Patent or in devices with angles close to that embodiment and do not apply to the range of angles which the Patent covers. In any event, I am not persuaded that the suggested differences would have prevented the skilled person from taking the obvious steps which would have brought the device within the pursuer's inventive concept. The Wood device with a camera in its fixed form provided such housing and protection which could equally have been used on a camera in a fixed position on a generally curved blade, including an anatomically-shaped blade.

[160] Even if I am wrong about the challenge on the ground of obviousness succeeding on the pursuer's construction of the Patent, the risk of such a challenge supports the construction of the Patent which I favour. On that construction, the Patent would not be exposed to the obviousness challenge as I have not taken an extended meaning of "substantially straight" and I do not think that the Wood patent made obvious the creation of an angulated blade comprising two substantially straight portions which were generally equal in length. The obviousness challenge therefore fails.

(d) The AVIL device

[161] I described the AVIL device in paragraph [70] above. The defender cites it in support of a challenge on the ground of obviousness.

[162] The AVIL was intended primarily for direct laryngoscopy but, where it was not possible to obtain an adequate direct view of the glottic aperture, its imaging system using a video endoscope enabled the clinician to see the relevant site. It differed from the Patent in that it used fibre optics to obtain a view which a video camera at the proximal end of the cable presented on a monitor. It comprised a modified Macintosh blade in which the distal portion was relatively straight compared to the curved proximal portion and was angulated upwards to create an angle similar to that in the preferred embodiment of the Patent if an angle were measured from the plane of the curved proximal portion. In his article on the device Dr Weiss referred to the Bullard and Upsher laryngoscopes and the Wuscope as devices which were designed to view the vocal cords "round the corner", but observed that, as they were not suitable for direct laryngoscopy, they were not used for routine tracheal intubation.

[163] Mr Lake submitted that it was obvious to modify the AVIL by replacing the fibre-optic cable with a camera such as the CCD or CMOS chips in order to achieve a result which fell within the pursuer's inventive concept. He relied in this regard on Dr Henderson's evidence that the use of such a camera as a distal viewer would have been obvious to the skilled person who was aware as part of his common general knowledge of the use of cameras in that way in gastrointestinal endoscopy.

[164] I am satisfied that, on my construction of the Patent, the AVIL did not render Claim 1 of the Patent obvious. I accept that at the priority date it may have been obvious that one could have substituted a video camera for the fibre-optic device within the blade of the AVIL. But when regard is had to the geometric specification of Claim 1, including substantially straight base and lifter portions and also the general equality of length of the two portions, it is not clear to me that the skilled person would have considered that it was obvious or worth trying to move from the shape of the AVIL to that set out in Claim 1 of the Patent. The challenge on the ground of obviousness therefore fails.

[165] More finely balanced arguments would have arisen if I had been content to accept the pursuer's inventive concept (paragraph [137] above) and the pursuer's interpretation of the expression "substantially straight" in relation to the base portion as an accurate description of the invention. The skilled person would have been entitled to conclude that the AVIL with a video camera, which was located at and in substitution for the distal end of the fibre-optic cable, would have fallen within the pursuer's inventive concept. The skilled person might also have observed the cross reference in Dr Weiss's text to the rigid laryngoscope blades, such as the Bullard, and have attempted to place a camera in a similar position on such an anatomically-shaped blade. Unless it were demonstrated that the AVIL could not give a perspective view (and that is not clear from its shape and the location of the lens), I think there would have been substance in an obviousness challenge.

(e) The Moritex patent

[166] I described the Moritex patent in paragraph [71] above. The defender cites it in support of a challenge on the grounds of both anticipation and obviousness.

[167] Again the defender's case of anticipation arises only if one adopts the pursuer's inventive concept as an accurate statement of the invention in Claim 1 of the Patent. Mr Lake's argument was essentially the same as that which he advanced in relation to the Wood patent. As I do not favour the pursuer's formulation of the inventive concept in Claim 1 of the Patent, that challenge fails.

[168] Similarly, I do not think that the Moritex patent rendered Claim 1 of the Patent obvious as I have construed it.

[169] I turn to assess obviousness in the context of the pursuer's inventive concept. Dr Walls and Dr Henderson agreed that the Moritex patent showed a Macintosh-type curved blade. Dr Henderson gave evidence that, on the pursuer's approach, the Moritex patent anticipated the Patent. Mr Lake recognised that the Moritex patent was concerned principally with the camera rather than the shape of the blade. He observed that the camera was depicted in a position that was significantly drawn back from the distal tip of the blade and that it showed two portions of the blade, namely the part distal to the camera face and the part proximal to it. He observed that the diagrams suggested that the part of the blade distal to the camera had little curvature while the proximal part had greater curvature. Thus it was possible to ascertain two planes intersecting at an angle.

[170] Dr Walls's evidence was that the blade shown in the Moritex patent did not have two portions and was arcuate-shaped rather than angulated. It taught the modification of existing direct laryngoscope blades rather than creation of a blade designed for indirect visualisation only. The Moritex patent was seeking to substitute a camera for fibre-optic viewers to improve image quality and resolution. It appeared to envisage the blade being used primarily to examine the larynx rather than to intubate, although it allowed for intubation.

[171] In my opinion the Moritex patent by itself would not have made obvious the inventive concept on which the pursuers rely, in so far as it is based on the preferred angle of 45º. As Dr Walls stated, the Moritex patent taught the use of the camera in place of a fibre-optic cable and did not address the shape of the blade in which the camera was placed. But its emphasis on the use of a camera in place of fibre-optic devices would point the skilled person towards the adaptation of the anatomically-shaped rigid fibre-optic laryngoscopes which were within the common general knowledge. It was clear from Dr Henderson's oral evidence that on the pursuer's functional approach it was possible to identify a base portion and a lifter portion on the curved Bullard blade and to define an angle between the planes of those portions and that the Glidescope Cobalt (if it were an embodiment of the Patent as the pursuer claims) had a shape very similar to the Bullard blade. Thus if I had accepted the pursuer's approach to the inventive concept, the combination of the Moritex patent and the common general knowledge of anatomically-shaped blades would have exposed the invention to a possible challenge on the ground of obviousness. The defender's obviousness challenge would have been similar to its challenge in relation to the Wood patent and would, subject to the qualification below, have had broadly similar prospects of success. That qualification is that there would be an argument that the Moritex patent combined with knowledge of the anatomically-shaped blades of the rigid fibre-optic laryngoscopes, which I have accepted was part of the common general knowledge, would not have rendered obvious the positioning of the camera at or near the middle of the blade so as to obtain a perspective view. Unlike the Wood patent, which taught or encouraged the addressee to look for a preferred view when positioning the camera, the Moritex patent, focusing as it did on the use of the camera, did not address the quality of the view which could be obtained from particular positions on the blade.

[172] It follows from my construction of Claim 1 of the Patent, which emphasises the geometric descriptions of the device, that the defender's challenge to the validity of the Patent fails. It is therefore unnecessary to consider whether any of the other claims have independent validity. Had I been required to do so, I would not have been inclined to hold claims 11-13 to be independently valid given the range of angles covered by the claims and the pre-existence of angulated straight blades in the form of the Siker laryngoscope and the Belscope (see paragraphs [59]-[62] above). Assuming the invalidity of Claim 1, I do not see how the angles claimed create "a uniquely configured instrument" as the pursuer asserts. Further, the anatomically-compatible shaping of a blade for use as an indirect laryngoscope was not new as the rigid fibre-optic laryngoscopes, such as the Bullard, were part of the prior art.

[173] Claim 17 might be independently valid if the prior art did not show a device with wireless connection to a monitor. There was some argument as to whether the Moritex patent covered such remote connection but I did not hear sufficient argument on the matter to form a clear view about the prior art and whether remote connection was obvious. Professor Roberts's evidence that the remote monitor was not obvious rested on his assessment of the identity and experience of the medical device engineer which I have held was understated (see paragraph [81] above). I discuss below the proposed claim 18 when I consider the pursuer's application to amend the Patent. See paragraphs [187]-[200] below.

Added Matter

[174] The defender also challenges the validity of the Patent on the ground of added matter.

(i) The law in relation to added matter

[175] Section 72(1)(d) of the 1977 Act empowers the court to revoke a patent if the matter disclosed in the specification of the patent extends beyond that disclosed in the application for the patent. As stated below, section 76(3) forbids the allowance of amendment which discloses such added matter. The established test for examining whether a patent involves the addition of subject matter was stated by Aldous J in Bonzel (T.) v Intervention Ltd (No 3) [1991] RPC 553 (at p.574) in these terms:

"The decision as to whether there was extension of disclosure must be made on a comparison of the two documents read through the eyes of a skilled addressee. The task of the court is threefold:

(a)   To ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application.

(b)   To do the same in respect of the patent as granted.

(c)   To compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition. The comparison is strict in the sense that subject matter will be added unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly."

[176] When considering added matter as a ground of challenge to a patent, the court asks whether the skilled person would, upon looking at the specification, learn anything about the invention which he would not learn from the application filed: Vector Corporation v Glatt Air Techniques Ltd [2008] RPC 10, Jacob LJ at paragraphs 4 and 8. When considering added matter in the context of a proposed amendment the same test is applied to the amended specification. The idea underlying article 123(2) of the European Patent Convention, on which section 76(3)(a) is based, is that the applicant should not be allowed to improve his position by adding subject matter not disclosed in the application as filed, which would give him an unwarranted advantage and could be damaging to the legal security of third parties relying on the content of the original application: Vector Corporation at paragraph 7; M-Systems Flash Disk Pioneers Ltd v Trek 2000 International Ltd [2008] RPC 18, Kitchin J at paragraph 33.

(ii) The challenge

[177] Mr Lake sought revocation of the Patent on the ground that the specification of the Patent extended beyond that disclosed in the application for the patent. In particular, he submitted that the Patent added matter to the application PCT/CA01/01135 in that the Patent in Claim 1 referred to a "substantially straight" base portion whereas in the application there was no geometric description of the base portion. The relevant text of the application was:

"The arm includes an elongate base portion 202, and a lifter portion 204 extending therefrom as best shown in Fig 7."

Figure 7 of the application and Figure 7 of the Patent are identical and, as I have said, show a straight base portion except where it intersects with the handle and with the lifter portion. Mr Lake submitted that if the phrase "substantially straight" in Claim 1 of the Patent were to be interpreted as allowing the degree of curvature for which the pursuer argued, the use of that phrase amounted to added matter.

[178] I accept the defender's submission that Figure 7 does not allow for a range of departures from straight which would support the degree of curvature for which the pursuer argued. I was not persuaded by Professor Roberts' suggestion that the figure contained limits of deviation and that a curved blade which remained within those limits was encompassed by the drawing. I am satisfied that Figure 7 does not clearly and unambiguously disclose significant curvature. In my opinion the expression "substantially straight" contains words of limitation which are consistent with what Figure 7 teaches. As I have already concluded that the expression "substantially straight" does not bear the further extended meaning for which the pursuer has argued, based on a functional interpretation, I am not persuaded that the inclusion of the expression added subject matter to the depiction of the base portion in figure 7 of the application and the Patent. The added matter challenge therefore fails.

Amendment of the Patent

[179] The pursuer has sought to amend the Patent under section 75 of the 1977 Act and Rule of Court 55.5(6). The application sought to amend certain paragraphs of the specification and also certain claims. The Board of Appeal of the EPO allowed amendments to claims 1, 3, 6, 8, 13, 16 and 18 of the patent as granted. Those are no longer in issue. The defender opposes only the addition of new claims 18 and 19. I see no reason not to allow the proposed amendments to the description in the specification, which in large measure flow from the amendment of the claims which the EPO has allowed. An issue about the text of the description might have arisen if I had found that amended Claims 12 and 13 were independently valid; but I have not. I therefore confine my discussion to the proposed claims which the defender opposes.

(i) The law in relation to amendment

[180] The provisions of the 1977 Act which are relevant to amendment by the court in the context of revocation proceedings are as follows. Section 75 provides so far as relevant:

"(1) In any proceedings before the court or the comptroller in which the validity of a patent may be put in issue the court or, as the case may be, the comptroller may, subject to section 76 below, allow the proprietor of the patent to amend the specification of the patent in such manner, and subject to such terms as to advertising the proposed amendment and as to costs, expenses or otherwise, as the court or comptroller thinks fit....

(3) An amendment of a specification of a patent under this section shall have effect and be deemed always to have had effect from the grant of the patent. ...

(5) In considering whether or not to allow an amendment proposed under this section, the court or the comptroller shall have regard to any relevant principles applicable under the European Patent Convention."

Section 76(3) provides:

"No amendment of the specification of a patent shall be allowed under section 27(1), 73 or 75 if it -

(a) results in the specification disclosing additional matter, or

(b) extends the protection conferred by the patent."

[181] The court has a discretion in determining whether to allow an amendment, if it does not fall within the prohibitions in section 76(3). As Mr Lake submitted, in Kimberly-Clark Worldwide Inc. v Procter & Gamble Ltd [2000] RPC 422, Aldous LJ observed (at p.435) that while the 1977 Act should not be interpreted so as to be different to the European Patent Convention, that Convention had no provision corresponding to section 75 and the EPO had no equivalent jurisdiction. He held that the discretion to refuse amendment in the public interest under section 75 was as wide as it had been under the Patents Act 1949.

[182] But section 75(5) has been introduced since that decision by section 2 of the Patents Act 2004, and it is not clear to what extent that amendment has curtailed the discretion of a United Kingdom court: Terrell on the Law of Patents (16^th ed.) paragraph 9-74. In the Encyclopaedia of United Kingdom and European Patent Law (at paragraph 7-201f) the authors suggest that undue delay in amendment remains relevant but that the conduct of the patentee would otherwise not be relevant. In Zipher Ltd v Markem Systems Ltd [2009] FSR 1, Floyd J opined (at paragraphs 197-219) that the EPO had regard to (i) the appropriateness of the proposed amendments to opposition proceedings, (ii) their necessity, and (iii) procedural fairness, and that the discretion of the domestic judge to refuse amendments which comply with the Act had been limited to those matters.

[183] As no issue of the behaviour of the pursuer has been raised in the context of the exercise of the court's discretion, it is not necessary for me to decide if the obligation to have regard to relevant principles applicable under the European Patent Convention restricts the court to the consideration of such principles alone. I would be inclined to think that it did not or that the concept of appropriateness was sufficiently broad to cover many matters; but I express no concluded view.

[184] The onus is on the patentee to establish that the amendment should be allowed: Smith Kline and French Laboratories Ltd v Evans Medical Ltd [1989] 1 FSR 561, Aldous J at p.569. Full disclosure of the circumstances occasioning the amendment is required: Oxford Gene Technology Ltd v Affymetrix Inc (No 2) [2001] RPC 18 (CA) at p.310, and M-Systems Flash Disk Pioneers Ltd v Trek 2000 International Ltd (supra), Kitchin J at paragraph 105.

[185] In assessing the appropriateness of an amendment it seems to me that the court should properly have regard, among other things, to the effect of the amendment on the validity of the patent, were it to be amended. In this case, as set out below, the defender challenges the sufficiency of proposed claim 18. Section 72(1) of the 1977 Act empowers the court to revoke a patent if:

"(c) the specification of the patent does not disclose the invention clearly enough for it to be performed by a person skilled in the art."

[186] Thus, if an amendment were to invalidate a patent through insufficiency, the amendment should not be allowed.

(ii) Claim 18

[187] Proposed claim 18 is in the following terms:

"The intubation instrument of any one of claims 1 to 5 and 8 to 17, wherein a transparent protective sheath is positioned over the instrument to facilitate cleaning and to provide sterile multiple use of the instrument."

[188] In relation to this proposed claim the defender's submissions were (a) that the court should exercise its discretion to refuse the amendment because the claimed device was obvious, (b) that the pursuer had not disclosed the basis on which it sought the amendment, (c) that there was no necessity for the proposed claim to meet any challenge to the validity of Claim 1 and it should not be allowed if, by being an independently valid claim, it extended the scope of the protection of the Patent, (d) that by not confining the claim to a "tightly fitted" sheath, the amendment contained a claim in respect of types of sheath which were not previously mentioned and thus contained added matter, and (e) that the proposed claim suffered from insufficiency as it did not teach how to construct a tightly fitting sheath which was capable of fitting over the angulated base and lifter portions.

[189] The reason which the pursuer advanced in its written application for amendment was that "the amendments are sought, inter alia, in order more clearly to distinguish the Patent over the documents cited as prior art by the defender in the present proceedings and, in particular, UK Patent Application GB 2 086 732A". That is a reference to the Bellhouse patent. The other reasons covered by the phrase, "inter alia", were not disclosed. I am prepared to judge the necessity of the amendment and its appropriateness against the reason disclosed and those advanced by Mr Currie in his submissions.

[190] Dr Walls gave evidence that the proposed Claim 18 of the Patent allowed for a disposable transparent sheath to cover the blade and viewer assembly, which would allow multiple, consecutive uses of the instrument without the need for cleaning between uses. This saved time and also allowed the use of the instrument outside a hospital environment. Professor Roberts similarly saw the proposed claim as allowing for multiple use of the instrument. He opined that while disposable sheaths were known, they were usually employed where the device they were sheathing was difficult or impossible to sterilise. As the sheath was not absolutely necessary for the laryngoscope, he considered that it was not an obvious addition but involved an inventive step.

[191] Dr Henderson did not agree that the proposed claim involved an inventive step. He gave evidence that by the late 1990s the growing awareness of prion diseases, such as CJD, had heightened clinicians' awareness of the need for better sterilisation of laryngoscopes between each use. Sterilisation could destroy viral disease on many devices but not remove protein deposits. By the priority date Penlon Limited had produced a loosely fitting sheath, called the "Larygard", which could be placed over a Macintosh blade. It was translucent rather than transparent. It was not popular as it reduced the transmission of light from the bulb in the Macintosh and it had no elasticity. But the idea of putting a sheath over a laryngoscope blade was not novel.

[192] The defender produced in evidence a copy of an advertisement of the Larygard which was undated. The advertisement explained that the Larygard offered a disposable sheath which gave a perfect fit over all European Macintosh 3 blades and provided cross-infection protection against HIV, hepatitis, CJD and others.

[193] Mr Currie challenged the adequacy of the defender's evidence in this regard, submitting that it was insufficient to date the Larygard advertisement only on Dr Henderson's oral evidence of his recollection that it was marketed before 2000. But Dr Henderson referred to the Larygard being available at the priority date in his supplementary report and the defender had included that assertion in its answers to the application to amend. The pursuer led no evidence to suggest another date or challenged Dr Henderson's recollection. I therefore see no reason to question Dr Henderson's evidence in this regard.

[194] In relation to the challenge for added matter, the patent application PCT/CA01/01135 referred to the possibility of placing a sheath over "the assembly" in these terms:

"A tightly fitted, transparent protective sheath (not shown) may be positioned over the assembly to facilitate cleaning and provide sterile multiple use of the device. The sheath is tightly fitted over the lens of the camera to prevent it from encumber [sic] the view. Preferably, the sheath is a transparent polymer, such as plastic, which sheds mucus and blood, has little tendency to fog during use, and equilibrates rapidly to airway temperature."

This was repeated in paragraph 54 of the Patent. The patent application also on page 4 stated:

"A transparent protective sheathing may be positioned over the assembly to facilitate cleaning and provide sterile multiple use of the device."

[195] I am satisfied that the amendment if allowed would not add subject matter by omitting any reference to "tight fitting" in the proposed claim. I accept the pursuer's submission that the skilled person would know that if the sheath were to operate effectively there would have to be a tight fit between the instrument and the sheath at some point. In my view the reference in the application and the specification to a tight fit did not require the sheath to fit tightly to the instrument all along its length. Rather, it required a tight fit (i) at or near its proximal end to hold it in place, (ii) over the camera lens, as stated, and (iii) where it covered the distal end of the lifter portion. Accordingly the defender's challenge (d) fails.

[196] If I am correct in that construction of the patent specification, no question of sufficiency would arise in relation to the creation of the sheath to slip over an angulated blade made up of two substantially straight portions if the angulation were limited. I consider that a skilled person who was a medical device engineer would have been able to create such a device at the priority date. The skilled person, while not inventive, is not required to perform the invention without any trial or experiment; he is also expected to display a reasonable degree of skill and common knowledge of the art. See Mentor Corporation v Hollister Inc. [1993] RPC 7, Lloyd LJ at pp.10-13. But no guidance is given in the Patent on how to create such a sheath when the angle, while remaining acute, approached 85º. It seemed to me that an issue of sufficiency might arise if the sheath had to be slid into the blade from the distal end. However Professor Roberts gave evidence, which was not challenged, that a rigid sheath could be manufactured from several parts which were then applied together to make a seal. How practical it would have been to use such a sheath was not explored; but I am prepared to accept Professor Roberts' view that the skilled medical device engineer could create such a device at the priority date. Accordingly challenge (e) fails.

[197] In relation to the challenge on the ground of obviousness, Mr Currie submitted that the obviousness of a proposed amendment was not a ground of opposition to its introduction. In certain circumstances that may be so. But obviousness is not irrelevant; if an amendment were put forward as an independent inventive step, as Professor Roberts argued, obviousness would undermine the independent validity of the proposed claim. Mr Lake referred to Chinoin's Application [1986] RPC 39 in support of the contentions that, because the claim was obvious, (i) the court should exercise its discretion against the amendment or (ii) if allowed, the claim should be revoked. But in that case (at pp.42-43), the Comptroller held, in the context of an added matter challenge, that the fact that the proposed additional information was obvious did not enable the court to allow an amendment if the information was not already known. Something which was obvious could still be added matter. He was not addressing the separate question whether obviousness was a ground for refusing an amendment or revoking a claim. Where the claim is a dependent claim and is seeking to apply existing technology, or an obvious addition to existing technology, to the invention, it is not apparent to me that obviousness is a ground for revoking such a claim. Challenge (a) therefore fails.

[198] So far as the question is one of discretion, I do not see the necessity of the proposed amendment to resist a challenge to validity based on the Bellhouse patent or the other prior art, which did not anticipate or render obvious the Patent. The pursuer advanced no other case of necessity or any grounds which made it appropriate to allow the amendment in the face of the challenge to the validity of the Patent.

[199] The Patent as initially drafted sought no protection for the use of a sheath which was mentioned in the description in the specification. Mr Currie suggested in his oral submissions that the proposed claim placed a limitation on Claim 1 but I cannot see how that is so. Prima facie the inclusion of the proposed claim extends that protection in breach of section 76(3)(b) of the 1977 Act by including within the claims for a monopoly the use of a sheath on the device. The pursuer has put before me nothing to undermine that view. Put simply, without the addition of Claim 18, a person could market a sheath to cover the pursuer's product without infringing the pursuer's monopoly; if the Patent were amended to include the claim, he could not do so. Mr Lake also submitted that the sheath, if inventive (and he submitted that it was not) was an additional invention. It did not restrict Claim 1. He suggested that if it were inventive, it was an example of collocation and referred to SABAF SpA (supra), Lord Hoffmann at paragraphs 17 to 26. If the proposed claim were to be construed as independently valid, by itself and also in combination with proposed claim 19, it would extend the protection conferred by the patent. Further, insofar as the proposed amendment when taken together with proposed Claim 19 was designed to bring within the scope of the Patent's monopoly a device such as the Cobalt or Ranger blade in which the sheath covers the handle and flexible video baton and provides the blade of the instrument, that also would involve extending the protection of the patent. I discuss this further in paragraphs [207] and [208] below.

[200] In the circumstances I am satisfied that the amendment if allowed would extend the protection of the patent contrary to section 76(3)(b) of the 1977 Act. If I am wrong about that and it were a matter of discretion, I am not persuaded of the appropriateness or necessity of the amendment. I do not therefore have to decide whether the proposed claim would have been independently valid.

(iii) Claim 19

[201] Proposed Claim 19 is in the following terms:

"The intubation instrument of any one of the preceding claims, wherein the camera is secured within a sealed chamber (224) within the arm (22)."

[202] The defender challenged the proposed amendment because (a) it contradicted Claim 1 which required that the camera be secured to the posterior side of the arm, (b) it would add new subject matter to the Patent, (c) if it were independently inventive, it would extend the protection of the Patent if Claim 1 were found to be invalid, (d) if the pursuer accepted that the proposed claim was not independently valid, it had stated no clear rationale for the addition of the claim, and (e) its contents were obvious. Section 76(3) prevented amendment on grounds (b) and (c). In any event, the court should refuse the amendment in the exercise of its discretion on any of grounds (a), (d) or (e).

[203] In relation to Claim 19 Professor Roberts expressed the view that the skilled addressee who was a medical device engineer would interpret Claim 1 as requiring that the camera would be sealed against the effects of body fluids, water, gases, and chemicals used in sterilisation, if it were to function properly. Thus putting the camera in a sealed chamber within the blade or arm would merely be one obvious method of achieving the requisite seal. In his opinion the amendment to include the claim did not add new matter or extend the scope of the patent as granted or as amended.

[204] The application (on p.18) stated (and paragraph 53 of the Patent's specification repeated):

"Preferably, the camera 80´ is secured within a sealed chamber 224 within arm 22, thereby protecting it from water, gasses, and chemicals used in sterilization procedures. More preferably, the chamber 224 contains nitrogen gas free from moisture, thereby avoiding undesirable condensation. Preferably, the CMOS or CCD camera body is also sealed."

[205] I have set out my interpretation of the phrase in Claim 1, "a viewer operably secured to the said posterior side", in paragraph [125] above. The proposed Claim 19 does not contradict Claim 1 as so construed. Nor is there added matter in the proposed claim over that disclosed in the application. Challenges (a) and (b) therefore fail.

[206] I do not see any basis for refusing the proposed amendment on the ground of obviousness. See paragraph [197] above. Challenge (e) therefore fails. But, in relation to challenge (d), I see no necessity for the amendment nor have I been given any basis on which to consider it to be appropriate. Professor Roberts opined that the proposed claim, by itself, would not be independently valid. I agree. Challenge (c) is therefore superseded.

[207] It appears to me that the rationale for the proposed claims 18 and 19, although not articulated by the pursuer in its pleadings, is to attempt to bring within the scope of the Patent a device such as the Glidescope Cobalt or Ranger, comprising as it does the separate sheath which both covers the handle and video baton and is the blade of the instrument. There was no suggestion in the patent application or the Patent that the sheath was to perform that role rather than provide a disposable cover for the whole of the instrument, including the blade. The proposed claims, if added by amendment, would have to be construed in that context. Proposed claim 18 speaks of the sheath covering the intubation instrument. But it is difficult to give content to the proposed amendments without having regard to the products which the pursuer has brought to the market since the priority date, and in particular the Cobalt/Ranger blade. The pursuer asserts independent validity for claim 18 and claim 19 appears to be linked to that claim. I am left with the strong impression that the two claims are advanced together to give protection to sheathed laryngoscopes such as the Glidescope Cobalt and Ranger.

[208] In the circumstances I am satisfied that the amendment to introduce proposed Claim 19 should not be allowed. Taken with proposed Claim 18, it may extend protection of the Patent and so fall foul of section 76(3)(b) of the 1977 Act. In any event, I am not persuaded of the necessity or appropriateness of the proposed amendment and in the exercise of the discretion which section 75 confers I refuse the application to amend this claim.

[209] As a result I allow only the uncontested changes proposed to paragraphs 13-17, 19, 21 and 49 of the specification set out in 6/362 of process.

Infringement

[210] That leaves only the question whether the defender's product infringes the Patent. Section 60 of the 1977 Act provides that, in relation to an invention which is a product, a person infringes a patent if, while the patent is in force, he

"makes, disposes of, offers to dispose of, uses or imports the product or keeps it whether for disposal or otherwise"

in the United Kingdom.

[211] The defender, as I have stated, manufactures and markets a laryngoscope known as the McGrath Series 5 laryngoscope ("MS5"). I attach as Appendix 9(i) and (ii) photographs of the MS5 assembled and in its component parts. It has a handle, a camera stick and a transparent disposable blade. The handle has a colour LCD screen attached. Unlike the Glidescope Cobalt, the length of the camera stick distal to the handle can be adjusted with three fixed settings. Thus the length between the handle and the distal end of both the camera stick and the instrument when the disposable blade is in place can be varied. The camera stick is curved over more than half of its length. Its curvature exceeds that of the standard Macintosh blade. The portion of the disposable blade which fits over the camera stick exhibits the same curve as the camera stick. The disposable blade is curved over approximately two thirds of its length and its distal portion is straight. That portion lies distal to the camera stick and both operates to elevate the epiglottis and allows the camera to give a view of the patient's relevant anatomy.

[212] The disposable blade has a flange which commences about 3 cm distally to the proximal end of the blade. It was suggested in evidence that the flange started 1 cm distally but I was not able to replicate that measurement on the blade in Pro 6/344, which was presented to me during the oral evidence. In many patients the proximal end of the flange is broadly the point at which the blade when fully inserted will be at the front of or just outside the patient's mouth.

[213] Dr Walls pointed out that the cameras in the MS5 and in the Glidescope GVL respectively were located substantially in the same place within the posterior side of their blades. He clearly demonstrated in his evidence that the MS5, when its camera stick and thus its blade were not extended, closely resembled the Glidescope GVL 3. He placed them side by side and observed the extent to which the blade of the MS5 matched that of the Glidescope GVL 3. He produced photographs of the Glidescope GVL 3 superimposed on the MS5 and vice versa to make his point, which I accept, of the striking similarity of the shape of the blades, and of the devices as a whole. He also produced a photograph of the MS5 superimposed on Figure 7 of the Patent which showed among other things that, when the camera stick of the MS5 was not extended, it generally fitted over the drawing and had its distal tip at almost the same place as the tip of the blade in figure 7. Professor Roberts expressed the view that the deviation between the MS5 blade and the Figure 7 drawing was not material because the figure was not an engineering drawing.

[214] Applying his functional construction of the Patent, Dr Walls suggested that the MS5 had all of the integers of Claim 1 of the Patent and infringed the Patent. He commented on videos of clinicians using the Glidescope and the MS5 and noted that in each case the clinician inserted the device along the midline of the patient's mouth and that there was virtually no movement of the patient's head. Thus, he argued, the devices were used in substantially the same way. Dr Frerk also gave evidence that the two devices were extremely similar in use. Professor Roberts expressed the view that the MS5 fell within the terms of Claim 1 of the Patent.

[215] It is not necessary to recite the evidence of the expert witnesses in detail as the issue turns ultimately on the proper construction of the claims of the Patent. As I have not accepted the pursuer's functional approach to the construction of key integers of Claim 1 or the inventive concept which the pursuer proponed, it follows that I do not accept the analytical superstructure erected thereon. It is therefore not necessary for me to set out and determine the differences of view between the pursuer's witnesses and Dr Henderson on these matters.

[216] I have held that the expression "substantially straight" in Claim 1 of the Patent does not bear the functional meaning which the pursuer asserts but, on the contrary, is to be treated as a deliberate geometric limitation of the scope of the claimed monopoly. See paragraphs [108]-[123] above. The proximal part of the blade of the MS5 from the handle to the point which equates with the distal end of the camera stick is not substantially straight but is clearly curved. Even if one measures from the start of the flange on the disposable blade to the latter point, which is the part which the pursuer equated with the base portion of the Patent, the blade is still curved rather than substantially straight.

[217] As I do not accept the pursuer's functional interpretation of the expression "base portion" in Claim 1 but see it as the part of the blade running from the handle to the proximal end of the lifter portion, I do not consider that the MS5 infringes the first of the characterising integers, namely that the length of the elongate lifter portion is about as long as the elongate base portion. Dr Henderson gave evidence, which I broadly accept, that the lifter part of the MS5 blade was about one-half the length of the proximal part of the blade which equated to the length of the camera stick, when camera stick was at the shortest adjustable setting and was fully covered by the disposable blade. On examining the blade in Pro 6/344 I found the lifter part of the blade to be about 5.3 cm in length and the rest of the blade on its anterior surface to be about 9cm in length.

[218] As the proximal part of the MS5 blade is curved, it is not at a defined angle to the lifter part as envisaged in Claim 1 of the Patent.

[219] It follows from the above that the MS5 does not infringe Claim 1 of the Patent. As the other claims are dependent upon Claim 1, the MS5 does not infringe the Patent.

[220] For the sake of completeness, I record very briefly certain views which I reached or would have reached on other submissions:

(i) I would not have accepted the defender's submission that the existence of three components of the MS5, namely the handle, the camera stick and the disposable blade excluded the MS5 from the scope of Claim1. Mr Currie submitted, and I accept, that the body of the device should be taken to encompass the whole of the device.

(ii) I accept that the devices described in the Patent, the Glidescope GVL and the MS5 could be used for both direct and indirect elevation of the epiglottis.

(iii) It also follows from my construction of the phrase "operably secured to said posterior side of said arm" in Claim 1 that I do not accept the defender's suggestion that the location of the camera within the blade of the MS5 would of itself remove the device from the scope of Claim 1.

(iv) I would not have accepted the defender's submission that the adjustable arm of the MS5 could exclude it from the scope of Claim 1 if the device otherwise infringed that claim. In my view the existence of three adjustable settings would be an immaterial variation.

(v) If I had accepted the pursuer's construction of the base portion in the Patent I would have treated the equivalent on the MS5 as the distance from the proximal end of the flange to the part of the blade which equated with the distal end of the camera stick. I accept Dr Roberts's evidence that that length (at 5.8 cm) is about as long as the part of the blade from the point on the anterior surface of the blade at the distal end of the camera stick to the distal tip of the lifter (at 5.6 cm). While my measurement of the latter length was slightly shorter, I consider that to be immaterial.

(vi) Had I concluded that the MS5 infringed Claim 1 of the Patent, I would have held that it also infringed Claims 4, 5 and 8-16 of the amended Patent. The defender submitted that, if the MS5 infringed Claim 1, it would not infringe claims 11-13 because of the difficulty which the pursuer's witnesses had had in measuring the defined angle from a curved base portion. But I am not persuaded that that difficulty would have prevented there being a defined angle, if the pursuer's construction were otherwise correct.

(vii) Had I allowed the amendment of the Patent to include Claim 18 I would not have interpreted the sheath in that claim as encompassing a disposable blade such as in the Glidescope Cobalt. Proposed Claim 18 refers to the sheath being placed over the intubation instrument and not just a component thereof, namely the handle and video baton.

Conclusion

[221] I have held the Patent to be valid (paragraph [172] above), allowed the patent to be amended only to the extent of the uncontested changes to the description in the specification (paragraph [209] above) and have concluded that the MS5 does not infringe the Patent (paragraph [219] above).

[222] I therefore (i) sustain the pursuer's second, third and fourth pleas in law in the counterclaim and repel the defender's pleas in law therein and assoilzie the pursuer from the conclusion of the counterclaim; (ii) allow the Patent to be amended only to the extent of the uncontested changes to paragraphs 13-17, 19, 21 and 49 of the specification as set out in 6/362 of process; and (iii) sustain the defender's second and fourth pleas in law in the principal action, repel the defender's third plea in law and the pursuer's pleas in law therein and assoilzie the defender from the conclusions of the summons.

[223] I will have the case put out by order to allow parties to make submissions on the issue of expenses.

Subject	Paragraphs
Introduction	1-5
Background: (i) endotracheal intubation	6-11
(ii) the laryngoscope	12-16
The Patent	17-22
Law: construction of patents	23-30
Law: the skilled addressee and common general knowledge	31-39
The role of expert witnesses	40-50
The prior art	51-71
The skilled person/skilled addressee	72-83
The common general knowledge	84-97
The Pursuer's product: the Glidescope	98-100
The interpretation of the Patent	101-127
The validity of the Patent:
(i) The statutory provisions	128-129
(ii) Anticipation	130-132
(iii) Obviousness	133-135
(iv) Applying the law to the case:
(a) The Bellhouse patent and Belscope	145-146
(b) The Bullard patents and laryngoscope	147-152
(c) The Wood patent	153-160
(d) The AVIL device	161-165
(e) The Moritex patent	166-171
Added Matter	174-178
Amendment of the Patent
(i) the law in relation to amendment	180-186
(ii) Claim 18	187-200
(iii) Claim 19	201-209
Infringement	210-220
Conclusion	221-223

Appendices

1. Pursuer's Patent Figure 7

2. Pursuer's Patent Figure 8

3. Pursuer's Patent Figures 11A and 11B

4. Bullard Laryngoscope

5. Wood patent figures 2 and 3

6. Wood patent figures 4 and 5

7. Moritex patent figures 1-3

8. Glidescope GVL laryngoscope

9 (i) and (ii). McGrath Series 5 laryngoscope