Case No: A3/2005/2193 and 2193(Y)

Neutral Citation Number: [2006] EWCA Civ 1715
IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
CHANCERY DIVISION (PATENTS COURT)
The Hon Mr Justice Pumfrey
HC 04 C00114, HC 04 C00689, HC 04 C00690
Royal Courts of Justice
Strand, London, WC2A 2LL

Friday 15th december 2006
Before :

THE RT HON LORD JUSTICE CHADWICK
THE RT HON LORD JUSTICE RIX
and
THE RT HON LORD JUSTICE JACOB
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Between :

	Halliburton Energy Services Inc	Appellant	
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	(1)	Smith International (North Sea) Limited
(2)	Smith International Inc
(3)	Smith International Italia SpA	Respond-ents	
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(Transcript of the Handed Down Judgment of
WordWave International Ltd
A Merrill Communications Company
190 Fleet Street, London EC4A 2AG
Tel No: 020 7421 4040  Fax No:  020 7831 8838
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Guy Burkill QC (instructed by Messrs Bristows) for the Appellant
Michael Tappin (instructed by the Treasury Solicitor) for the Comptroller of Patents

The Respondents were not present and were not represented

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Judgment
Lord Justice Jacob (giving the Judgment of the Court): 
1.	This is an appeal from part of a judgment of Pumfrey J, [2005] EWHC 1623 (Pat); [2006] RPC 25.    Halliburton, the patentees of two patents for rotary cone drill bits, sued Smith for infringement.  Smith counterclaimed for revocation.   Smith won, Pumfrey J holding that although some of Smith’s bits fell within the scope of the claims of the patents, both patents were invalid for lack of sufficiency.   
2.	Pumfrey J gave both sides permission to appeal but limited to principles of law.  Permission to appeal any issue of primary fact was refused.    Shortly thereafter the parties settled.   Halliburton nonetheless decided to pursue their appeal in respect of one of the revoked patents, No. EP 1,112,433, known as the “Force Balancing Patent”.   They do not challenge the finding that the other patent, the “Orientation Patent”, No. EP 1,117,894 is invalid.
The position of the Comptroller
3.	Pursuant to an interlocutory judgment in this case, [2006] EWCA Civ 185, it was held that this court will not restore a revoked patent by consent or by a purely administrative order.  The patentee must satisfy the Court of Appeal that the decision below was wrong.  Also pursuant to that decision, the Comptroller General of Patents was invited to consider whether he should play a part in the appeal, in effect representing the respondent, though exercising his own judgment as to which points it was proper to argue.  Mr Tappin summarised the Comptroller’s position thus:
“What we see ourselves as here to do is to help the court - to put the other side of the argument to the extent we think it should be put and to make such criticisms of Halliburton’s submissions as we believe appropriate.”
4.	This procedure has worked well.  We found Mr Tappin’s assistance to have been of great value.  We hope that the Comptroller will play a similar part in any future appeal where the respondent has settled and has no (or perhaps even a positive) interest in the appeal’s success.
The Scientific Adviser
5.	It was common ground that the subject matter of the case was highly technical and that the Court of Appeal would be assisted by a scientific adviser.  As is recounted in the judgment of this court, [2006] EWCA Civ 1599, handed down immediately before the substantive appeal started, Professor David Limebeer, Head of the Department of Electrical and Electronic Engineering and Professor of Control Engineering at Imperial College London, was appointed.  We sat with Professor Limebeer and also retired with him in order to gain his assistance.  Prior to the hearing, on his own initiative, he provided the court with some initial views in an e-mail set out as an appendix to that judgment.  Halliburton took the view that Professor Limebeer had strayed too far from merely acting as an adviser and asked the court for an adjournment so that a new and different scientific adviser could be appointed.  For the reasons given in that judgment the application was refused.
6.	Professor Limebeer provided us with a great deal of valuable background scientific understanding.  Following the hearing he set forth in a second note, (set out as an appendix to this judgment) the nature of the advice and instruction that we were given.  Mr Burkill QC, on behalf of Halliburton, did not during the course of his argument refer directly to the earlier note.    He did provide a written submission on the later note, observing at the outset “Halliburton welcomes the assistance which Professor Limebeer has provided to the Court of Appeal [in the note] and has no significant criticism of it.” We record that we have decided this appeal solely on the basis of the evidence given to the court below and the submissions made to us.  Professor Limebeer has played no part in the decision we have reached.
7.	We envisage that in the future, where a scientific adviser is appointed, a similar record of the part he or she has played will normally be provided to the parties with, of course, also an opportunity being given to them to comment on it.
Peripheral findings of invalidity
8.	In addition to finding the patent invalid for insufficiency, Pumfrey J also found a violation of Art.52 of the European Patent Convention (EPC) implemented by s.1(2) of the 1977 Act.  Mr Burkill said that this problem with validity could be overcome by a suitable amendment and so there was no point in pursuing an appeal on this point.  Halliburton have pending applications to amend, applications which only could become live if the main appeal on sufficiency succeeds.  
9.	It was common ground however, that no amendment could cure the finding of insufficiency.  So Halliburton must succeed on that issue if the patent is to be saved in any form.
10.	It should also be noted that Halliburton no longer pursue an appeal concerning the construction of some of the claims.   They accept Pumfrey J’s construction, to the details of which we shall come.
The law as to sufficiency
11.	Art.83 of the EPC provides that a patent application “must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art”.  This is implemented by s.72(1)(c) of the 1977 Act which makes failure to comply with that requirement a ground of revocation.
12.	This precise language is new.  However, the basic requirement, that a patent should teach the practice of the invention sufficiently well for the notional addressee to perform the invention is fundamental to the patent system:  the teaching is the price the patentee pays for his time-limited monopoly.   No one suggests that the EPC changed anything in relation to this topic.  Older English cases which contain useful discussions about the subject remain relevant in understanding the concept more fully.
13.	Pumfrey J  summarised the law [131-133]:
“[131]	It is a basic principle of patent law that the European patent application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Article 83 EPC transposed into section 14 of the 1977 Act). This requirement has long been fundamental. The sufficiency of a specification is a question of fact and necessarily depends upon the nature of the invention and the attributes of the skilled person. There is no general rule, and although statements like ‘you may not set a man a problem and call it a specification’ or ‘the skilled person must be enabled to perform the invention without prolonged research, enquiry and experiment’ give a flavour of the problem they do not really help (see Mentor v Hollister [1993] RPC 7 at 10-14). 
[132]	In the Mentor case, the Court of Appeal was attracted by the word ‘routine’, used by Aldous J at first instance. This word has the advantage that it enables a comparatively straightforward test along the lines of ‘does this specification require the addressee of the specification to carry out tests, or developments, that go beyond the routine?’ As Lloyd LJ said in that case, a phrase like ‘routine trials’ introduces a positive concept, easily understood and applied. Aldous J put it like this ([1991] FSR 557 at 561):
‘The subsection is concerned with the disclosure of the invention in the specification. Thus it is necessary to read the specification through the eyes of the skilled addressee to ascertain what is the invention that is disclosed. Even where patents relate to articles, the inventions disclosed in different specifications can be different in kind. For example, the invention disclosed may relate to an article which will perform a particular function or an article which is cheaper to make than similar articles. In the latter case, it is the very essence of the invention disclosed in the specification that the article can be made more cheaply and therefore to perform the invention the person skilled in the art must be able to make the article cheaply as described in the specification. In the former case, the person skilled in the art must be able to produce the article which will perform the function, as that is the invention disclosed.
The section requires the skilled man to be able to perform the invention, but does not lay down the limits as to the time and energy that the skilled man must spend seeking to perform the invention before it is insufficient. Clearly there must be a limit. The subsection, by using the words "clearly enough and completely enough," contemplates that patent specifications need not set out every detail necessary for performance, but can leave the skilled man to use his skill to perform the invention. In so doing he must seek success. He should not be required to carry out any prolonged research, enquiry or experiment. He may need to carry out the ordinary methods of trial and error, which involve no inventive step and generally are necessary in applying the particular discovery to produce a practical result. In each case, it is a question of fact, depending on the nature of the invention, whether the steps needed to perform the invention are ordinary steps of trial and error which a skilled man would realise would be necessary and normal to produce a practical result.
The section requires the skilled man to be able to perform the invention. Such a man is the ordinary addressee of the patent. He must be assumed to be possessed of the common general knowledge in the art and the necessary skill and expertise to apply that knowledge. He is the man of average skill and intelligence, but is not expected to be able to exercise any invention. In some arts he may have a degree, in others he will be a man with practical experience only. Further, in circumstances where the art encompasses more than one technology, the notional skilled person will be possessed of those technologies which may mean that he will have the knowledge of more than one person.’
[133]	All the same, one must be on one’s guard against formulations that gloss the statutory requirement as there is always a risk that they will end up being substituted for it. This is a particular risk where the subject of the specification is very complex and its development would anyway be expected to be accompanied by a great amount of work. What is ‘prolonged’ in this context? It is always necessary to keep a balance between the interests of the public and the interests of the patentee in the sense that it is necessary to guard against imposing too high a standard of disclosure merely because the subject matter is inherently complex. The general use of computers in modern technologies raises particular problems, because the writing of anything other than a trivial program requires a substantial amount of effort in writing and debugging (programming’s version of trial and error), even though much programming requires no creative thought and a competent programmer will be equipped with substantial experience in his area of expertise. When such a programmer forms part of the team which is the notional addressee of a computer-based invention, it is essential to form a view of his capabilities.”
14.	Mr Burkill, in his skeleton argument, advanced an argument to the effect that where the skilled addressee was taken to be a team (because more than one skill was involved) then the law requires one member of the team to be the “head” directing the others.  Here the suggestion was that the head of the team would be a rock bit engineer who would be directing a computer model designer as some kind of assistant.  That position was not pursued during the oral argument.  And rightly so.  If the addressee of a patent is a notional team of persons with differing skills, then it is a team with no boss.  Each member of the team is assumed to play his/her own part.  
15.	However, and this formed the basis of one of Mr Burkill’s main submissions, one must be careful to ensure that the notional member of the notional team confines his/her contribution to his/her own expertise.  There was no dispute that this was so in principle.  Mr Burkill’s submission was that the Judge had erred by preferring the evidence of Smith’s expert, Professor Newland, over that of Halliburton’s expert, Mr Hall, in areas where Professor Newland had no relevant expertise whereas Mr Hall did have that expertise.   Professor Newland’s expertise was that of an engineer and computer modeller, that of Mr Hall, rock bit design.   We will come to the detail later.
16.	Mr Burkill emphasised that the test of insufficiency was sensitive to the nature of the invention.   He referred us to what Lord Hoffmann said in Kirin-Amgen, [2004] UKHL 46, [2005] RPC 169:
“103. Whether the specification is sufficient or not is highly sensitive to the nature of the invention. The first step is to identify the invention and decide what it claims to enable the skilled man to do. Then one can ask whether the specification enables him to do it.”
17.	From this he sought to derive a proposition along the following lines:  if  implementation of the “concept” of the invention requires work, it does not matter how much work is required if it is not itself related to the concept, provided only that the work is “routine”.   When a hypothetical case of an inventive concept which would take 20 years of routine mathematical work to implement was put to Mr Burkill, he submitted that a patent for that concept would not be insufficient: “timescale does not come into it.”   He pointed to examples of technologies which inherently involved a lot of work such as some aspects of genetic engineering or pharmaceutical science where much routine work is involved in implementation.  He suggested that if there were some sort of limit on the amount and timescale of such work for a patent to be sufficient, then there would be areas of technology where one could not get patents.
18.	We do not accept that extreme submission.   Patents are meant to teach people how to do things.  If what is “taught” involves just too much to be reasonable allowing for all the circumstances including the nature of the art, then the patent cannot be regarded as an “enabling disclosure.”  That is the basic concept behind the requirement of sufficiency and one that lies at the heart of patent law (“central” as Lord Hoffmann put it in Biogen v Medeva [1997] RPC 1 at p.47).  The setting of a gigantic project, even if merely routine, will not do.   Moreover the analogy with genetic engineering and pharmaceutical inventions is not apt.   The work that goes into bringing them to market relates to testing efficacy and safety – not in actually making the invented product.
19.	The European Patent Office test of “undue effort” is apposite for testing sufficiency.    It was developed principally to deal with claims of undue width or those limited by function– see e.g. GENENTECH/Human t-PA T 929/92.  But it is also of general application. It is another way of applying the very words of the objection which emphasise the question is one of degree (“clearly enough and completely enough”).   
20.	Of course it may be asked, how is one to say when the work involved to perform the invention is too much?   Justice Holmes expressed the problem of this sort of rather fuzzy borderline thus: 
“When he has discovered that a difference is difference of degree, that distinguished extremes have between them a penumbra in which one gradually shades into the other, a tyro thinks to puzzle you by asking you where you are going to draw the line and an advocate of more experience will show the arbitrariness of the line proposed by putting cases very near it on one side or the other”, Law and Science in Law Collected Legal Papers 1921, pp.232-233.
21.	The answer is that the line is one to be drawn by an exercise of judgment, taking into account all of the relevant factors, one of which is of course the nature of the invention itself and its field of technology.  But there are other factors too – for instance, the width of the patent claim or whether it has functional limitations which require too much work to explore.
22.	We would add one further comment here:  there is an interrelationship between obviousness and insufficiency.   At first blush one might suppose that an idea which requires masses of work to implement would be more readily rejected by, or less likely to occur to, the notional unimaginative skilled person/team who is the addressee than one which can be readily put into practice.   This produces an apparent paradox: the less sufficient the description, the less is an idea likely to be obvious.   The answer to the paradox is this:  that if the notional skilled person/team is one that is prepared to contemplate an immense amount of work, that attribute must also be considered part of the person/team’s consideration of what is obvious.   Obviousness and sufficiency of description must be considered by the same person/team.   
23.	The point could have been relevant here, as Mr Tappin pointed out.  For there was cited as part of an obviousness attack an earlier, non-enabling close proposal called Sandvik.   Mr Tappin suggested that if, contrary to the Judge’s findings, the patent in suit was sufficient to the notional team, the finding of non-obviousness over Sandvik ought to be revisited.  In the end it is not necessary to consider this point further.
Standard for an appeal about insufficiency
24.	There was no dispute about this.  A decision of insufficiency, like that on obviousness, involves an assessment and weighing of a number of factors.  Lord Hoffmann in Biogen v Medeva [1997] RPC 1 at page 45, put the position in relation to obviousness thus:
“The need for appellate caution in reversing the judge’s evaluation of the facts is based upon much more solid grounds than professional courtesy. It is because specific findings of fact, even by the most meticulous judge, are inherently an incomplete statement of the impression which was made upon him by the primary evidence.  His expressed findings are always surrounded by a penumbra of imprecision as to emphasis, relative weight, minor qualification and nuance (as Renan said, la vérité est dans une nuance), of which time and language do not permit exact expression, but which may play an important part in the judge’s overall evaluation.  It would in my view be wrong to treat Benmax as authorising or requiring an appellate court to undertake a de novo evaluation of the facts in all cases in which no question of the credibility of witnesses is involved. Where the application of a legal standard such as negligence or obviousness involves no question of principle but is simply a matter of degree, an appellate court should be very cautious in differing from the judge’s evaluation.”
The same reasoning obviously also applies to a decision about insufficiency and the House of Lords so held in SmithKline Beecham’s Patent [2006] RPC 323 at [38] in the speech of Lord Hoffmann with which the other members of the House all agreed on this point.
25.	At some points during the course of his argument, Mr Burkill sought to elevate into “a question of principle” what were really matters of weight in the overall evaluation of sufficiency.  In particular, his main point, that the evidence of Professor Newland had been given too much weight by the judge, at least in part, fell into this class.   As we have said we will return to this point.
The patent in suit
26.	Pumfrey J summarised much of the background common general knowledge to the patent.  Mr Burkill accepted as accurate [8-15]:
“[8] A bit in use carries a very substantial weight, called the weight on bit, or WOB. This weight is made up of the drill collar and the rest of the drill string and is controlled by a tackle at the top of the string, which is supported by the derrick.  Generally speaking there is a very easy introduction to the topic in the first chapter of the book called Rabia (‘Oilwell Drilling Engineering: Principles and Practice’ by Hussain Rabia), which is an undergraduate textbook located by Professor Cooper that is relied on as exemplifying the common general knowledge. 
[9] The manner in which the bit penetrates rock depends generally upon the geometry of the cones in the bit and the shape of the teeth. Rounded carbide inserts are used in hard rock: they break the rock by crushing it as the tooth rolls into contact with the formation. The forces employed are substantial: the weight on bit may be as high as 60 tonnes and the rate of  rotation 60 rpm. Softer formations require (in different degrees, depending upon the other drilling variables) a combination of both a crushing and a scraping action, for which the inserts or milled teeth will be more chisel-shaped. To ensure a degree of scrape, the cones are positioned so that their axes of rotation are not radial of the longitudinal axis of the hole, but are slightly offset so as either to lead or to lag a purely rolling motion, like this: 

[10] The diagram shows a linear offset from the centre axis: obviously this can also be viewed as an angular offset from the radius of the bit. Whatever the precise orientation of the cones, the bit must be designed so that the rows of teeth each do their share of the work. It is helpful to think of the bit rotating and penetrating the formation: if a row of teeth follows the same path as another both will be doing less work. The following example is given by Professor Cooper, in which Ring A is cut by the heel or gage row of all  three cones,  ring B by cone 1, rings C and E by cone 2 and ring D by cone 3:

[11] This diagram shows that the cones in a given bit are always different from each other. Each will be subjected to different dynamic conditions at the bottom of the hole, and there is no a priori reason to suppose that they will tend to wear evenly. The movement of the teeth is composed of a rolling about the cone axis and a translational component resulting in gouging and scraping, and is not easy to visualize. The force on the teeth in contact with the formation is itself the force which rotates the cones as the drill rotates.
[12] The economics of drilling require that the bit be withdrawn from the hole as infrequently as reasonably possible. The rate of penetration  needs to be as high as possible consistent with not causing premature wear of the bit, which obviously can destroy the advantage of a high rate of penetration if time is lost in early bit replacement. The process of ‘tripping’, which means the raising of the bit, is not trivial and is expensive—there may be thousands of feet of pipe to raise and uncouple. This means that durability of the drill is important and, with rate of penetration, is a primary concern of the user.
[13] Both before and after the priority date, the task of the manufacturer of drill bits has been to achieve durability with a good rate of penetration. It is impossible to monitor conditions at the bottom of a hole and very difficult to emulate them at the surface and so a designer’s job depended (and for those who do not use a simulation program, still depends) upon his ability to examine ‘dull’ (worn) bits and change the design in response to the pattern of wear he saw. Uneven patterns of wear  in the teeth and in the cone bearings will indicate the unsuitability of a particular design for a particular formation, and it is important to appreciate that a bit that is wholly inappropriate for one combination of formation, WOB and RPM may be entirely suitable to different combination of conditions.  Mr Hall had wide experience  of bit design and he provided this description of dull bit analysis:
‘61. Analyzing the performance of previous bit designs and examination of these dull bits was the primary method of determining changes for a new bit design. Various conditions observed on dull bits would indicate improvements that could be made on a new design. … 
62. For example, if a significant amount of breakage or chipping was consistently found in certain locations of the cutting structure of these dull bits, consideration would-be given to changing the number, shape or material used for the teeth in these locations. Adding rows of teeth to distribute the drilling forces may be considered. If this type of chipping or breakage was only found occasionally, the bit records for those bit runs. would be analyzed to determine if excessive WOB, excessive rotary speed or some other condition could have been the cause for the breakage. Consideration would also be given to the effects that changes to the tooth shape or quantity could have on the penetration rate of the bit. The experience and judgement of the bit designer would eventually be used to make changes to the design.
63. Another example would be if excessive wear was consistently noted in certain areas of the cutting structure, changes in the profile of the cone might be considered to decrease the amount of gouging and slicing that those teeth would experience. Again the effects that these changes would have on bit performance would be considered before changes would be made.
64. Unusual wear patterns observed on the bit would be considered in an attempt to determine possible causes for these conditions. Sharpening wear of the teeth on a bit can result from a condition known as "tracking". This condition is where as the cones rotate, one tooth falls into a crater on the bottom of the hole that has been caused by a previous tooth hitting at the same location. This condition causes a loss of penetration rate and results in wear to the cone shell as well as the teeth of the bit. Concentric rings worn into the cone shell can indicate that the bit is "running off-center" and is therefore not covering the bottom of the hole with cutting teeth in the desired locations as intended. This condition also results in decreased penetration rates and decreased bit life. Changes that would be considered to correct these conditions could include adding or removing. rows of teeth, changing the pitch scheme of teeth in the rows of teeth, changing the shape and length of teeth or other changes that a designers experience would indicate.’
[14] The manner in which the wear on a dull bit is reported is systematized. Both Professor Cooper and Mr Hall produced versions of a grading system proposed by the International Association of Drilling Contractors and are agreed that this system would be known to the skilled bit designer. Professor Cooper produced a ‘Bit Record’ which shows the history of a number of bits in a particular well, with the ‘Dull Cond[ition]’ specified for each.
[15] Accordingly, at the priority date drill bit design was in large part a matter for the skill, experience and intuition of the designer. Nobody has pointed to a comprehensive manual for drill bit designers, and I am sure that if one existed it would have been produced.”
27.	Pumfrey J next said this:
“[16] Both patents are addressed to persons wishing both to design and use simulation systems for drill bit design. Although the claims are directed to methods of design, and are hence the concern of a designer, the underlying equipment, if I can put it that way, is a simulation system that the patents say is new. The Force Balancing patent uses a ‘Rock Bit computer model’ for the purpose of working out the dynamics of a rotating bit and describes the design of a bit in terms of a ‘general nonlinear optimisation problem with bounds and nonlinear constraints’ applied to design variables, objectives expressed in terms of the design variables and the bounds on the design variables and the constraints on the system. [He then summarised the other patent].  Plainly, therefore, the specifications are addressed to (1) engineers who understand drilling and drill bits (2) engineers who understand simulations and their graphical display and (3) if not included among the others, engineers who can understand the mathematics of the interaction of a drill tooth and rock and design the software necessary to model the dynamics and kinematics of the bit. I return to this subject in more detail below.”
28.	Mr Burkill submitted that this was to put the wrong emphasis: that the real point of the patent was not a simulation system but the idea of using a simulation system so as to achieve equal forces on each cone of the bit.  We cannot see any force in this criticism.  A simulation model is plainly centrally important to the patent.  The fact that it is aimed at a system for achieving force balancing was plainly appreciated by the Judge:  he considered the patent in detail later.  The criticism is simply a complaint that he did not mention force balancing at this point.  But here the judge had yet to get into the detail of either patent.  The real point of this paragraph, namely the nature of the addressee of the patent, was not the subject of complaint.
29.	The Judge then went on to summarise the early part of the patent.  We borrow with gratitude, editing out portions no longer relevant particularly those referring to the Orientation Patent:
[18]	There are seven parts of the background section of the Force Balancing specification, concerned with rotary drilling generally (paragraphs [0002]-[0004]), drill string oscillation (paragraphs [0005] and [0006]), optimal drilling with various formation types (paragraphs [0007]-[0010]), roller cone bit design (paragraphs [0011]-[0014]), tooth design ([0015]-[0015] and bottom hole analysis (paragraphs [0018]-[0022]). 
We interpolate, that each of these seven parts are specifically given headings as set out by the Judge but each heading follows the word “Background”, e.g. “Background: Rotary Drilling.”  Turning back to the Judge:
[19]	The patent begins with a summary of the invention in paragraph [0001]:
‘[0001] The present invention relates to down-hole drilling and especially to the optimisation of drill bit parameters. In particular it relates to a roller cone drill bit, a method of designing the same, and a rotary drilling system.’
[20]	Paragraphs [0002]-[0004] set out very general background material, all of which I have covered in my discussion of the background above. The section on drill string oscillation is common general knowledge. Reduction of such oscillations is claimed as an advantage of drill bits designed according to the invention (paragraph [0034]), but it is not otherwise referred to in the specification.
[21]	The section concerned with Optimal Drilling with Various Formation Types (paragraphs [0007]-[0010]) is … all common general knowledge. Set out in summary form are the factors affecting how a formation is drilled and the types of bit suitable for soft formation (long teeth, high gouge), hard formation (short rounded teeth, no gouge) and medium formation (between the two). 
[22]	The next background section, ‘Roller Cone Bit Design’ …. was accepted by Mr Hall to be common general knowledge at the priority date. … I should refer to paragraphs [0011] and [0014]. Paragraph [0011] is concerned with the shape of the cones. It is pointed out that they need not be perfectly conical or frustoconical but may have what is called a ‘swollen’, that is bulging, axial profile. Apart from the shape of the cone itself, it is pointed out that both the angle between the axis of the cone and the radius of the bit (the offset angle) and the angle between the axis of the cone and the plane of the bottom of the hole (the journal angle, plainly related to the angle of the cone) are design parameters and affect the rolling of the cone, which, because it cannot necessarily roll true, causes gouging and scraping which, as is pointed out, is complex in nature.
[23]	Paragraph [0014] outlines the interrelationship of these design parameters and the effect of varying them. Two examples are given: cone angle and offset, which it is pointed out can be modified so as to increase or decrease the amount of bottom hole scraping. The other example is tooth length:
‘Many other design parameters are limited in that an increase in one parameter may necessarily result in a decrease of another. For example, increases in tooth length may cause interference with the adjacent cones.’
[24]	Paragraphs [0015] to [0017] are concerned with tooth design. Although the other paragraphs just set out a summary of the common general knowledge in respect of the range of shapes of teeth and their relationship to the formation intended to be drilled, I should just refer briefly to paragraph [0017] because the shape of the tooth and its interaction with the formation is important.
‘Chisel shaped inserts have opposing flats and a broad elongated crest resembling the teeth of a steel tooth bit. Chisel shaped inserts are used for drilling soft to medium formations. The elongated crest of the chisel insert is normally oriented in alignment with the axis of cone rotation. Thus, unlike spherical and conical inserts the chisel insert may be directionally oriented about its center axis. (This is true of any tooth which is not axially symmetric.) The axial angle of orientation is measured from the plane intersecting the center of the cone and the center of the tooth.’
[25]	There is no doubt that oriented teeth were part of the common general knowledge of the designer. The angle of orientation affects the interaction of tooth and formation, and hence the relative movement (both rotational and translational) of the cone as the bit rotates. The gouging motion represents a translational movement between the tooth and the hole bottom. The movement of the tooth in the formation between the moment the tooth enters the formation and the moment it leaves takes a time and covers a distance determined by  the rotation of the cone as it skids round the bottom of the hole. In the absence of a gouging motion, it should be remembered that the tooth movement can be visualised as a rolling movement about the point of the tooth, a movement whose translational element is small. The movement of the tooth in the coordinates of the hole bottom is shown by Professor Newland in Figure 7 in his principal report, explained further at transcript 1047 line 22.
[26]	The final section on background, “Bottom Hole Analysis’, sets the scene for the description of the invention. Paragraph [0018] does not call for much comment: it trivially points out that bit design affects rate of penetration, and that rate of penetration plays a ‘significant role’ in the economics of drilling a well.
[27]	Paragraph [0019] begins to approach the heart of the invention:
‘[0019] It has long been desirable to predict the development of bottom hole patterns on the basis of the controllable geometric parameters used in drill bit design, and complex mathematical models can simulate bottom hole patterns to a limited extent. To accomplish this it is necessary to understand first, the relationship between the tooth and the rock, and second, the relationship between the design of the drill bit and the movement of the tooth in relation to the rock. It is also known that these mechanisms are interdependent.’
This passage acknowledges the existence of ‘complex mathematical models’ that simulate bottom hole patterns. The bottom hole pattern is the cutting pattern left by the teeth in the formation at the bottom of the hole as the bit, subject to the WOB, rotates. The passage points out that in order to simulate the bottom hole pattern two things must be known: the way in which the tooth interacts with the formation and second ‘the relationship between the design of the drill bit and the movement of the tooth in relation to the rock’. The specification acknowledges that it is known that these mechanisms are interdependent, and it could not be otherwise, because the forces acting on a cone are made up of the forces transmitted by the leg of the bit and the drag caused by the passage of the teeth through the rock along a path constrained by the geometry of the bit as it rotates in the hole.
[28]	In paragraph [0020] the specification continues with a description of the work done on these two problems, that is, the way in which the tooth interacts with the formation and the relationship between bit design and the movement of the tooth in relation to the rock:
‘[0020] To better understand these relationships. much work has been done to determine the amount of rock removed by a single tooth of a drill bit. As can be seen by the forgoing discussion, this is a complex problem. For many years it has been known that rock failure is complex, and results from the many stresses arising from the combined movements and actions of the tooth of a rock bit. (Sikarskie, et al, PENETRATION PROBLEMS IN ROCK MECHANICS, ASME Rock Mechanics Symposium. 1973). Subsequently, work was been done to develop quantitative relationships between bit design and tooth-formation interaction. This has been accomplished by calculating the vertical, radial and tangential movement of the teeth relative to the hole bottom to accurately represent the gouging and scraping action of the teeth on roller cone bits (Ma, A NEW WAY TO CHARACTERIZE THE GOUGING SCRAPING ACTION OF ROLLER CONE BITS Society of Petroleum Engineers No 19448, 1989). More recently computer programs have been developed which predict and simulate the bottom hole patterns developed by roller cone bits by combining the complex movement of the teeth with a model of formation failure (Ma THE COMPUTER SIMULATION OF THE INTERACTION BETWEEN THE ROLLER BIT AND ROCK Society of Petroleum Engineers No 29922, 1995). Such formation failure models include a ductile model for removing the formation occupied by the tooth during its movement across the bottom of the hole and a fragile breakage model to represent the surrounding breakage.
[0021] Currently roller cone bit designs remain the result of generations of modifications made to original designs. The modifications are based on years of experience in evaluating bit run records and dull bit conditions. Since drill bits are run under harsh conditions, far from view, and to destruction it is often very difficult to determine the cause of the failure of a bit. Roller cone bits are often disassembled in manufacturers' laboratories, but most often this process is in response to a customer's complaint regarding the product, when a verification of the materials is required. Engineers will visit the lab and attempt to perform a forensic analysis of the remains of a rock bit but with few exceptions there is generally little evidence to support their conclusions as to which component failed first and why. Since rock bits are run on different drilling rigs in different formations under different operating conditions it is extremely difficult [to] draw conclusion[s] from the dull conditions of the bits. As a result, evaluating dull bit conditions, their cause and determining design solutions is a very subjective process. What is known is that when the cutting structure or bearing system of a drill bit fails prematurely it can have a serious detrimental effect of the economics of drilling.’
[29]	The two paragraphs appear to recognise both that numerical techniques exist to permit the prediction and simulation of bit action on formation by combining the movement of the teeth with a model of how the formation fails under the action of the teeth, and that these techniques have been incorporated in the computer program referred to in the Ma Paper. It is suggested that what is lacking is a way of using these techniques to replace the methods of design from bit analysis described in paragraph [0021] and that this is described in paragraph [0022]:
‘[0022] Though numerical methods are now available to model the bottom hole pattern produced by a roller cone bit there is no suggestion as to how this should be used to improve the design of the bits other than to predict the presence of obvious problems such as tracking. For example the best solution available for dealing with the problems of lateral vibration is a recommendation that roller cone bits should be run at low to moderate rotary speeds when drilling medium to hard formations to control bit vibrations and prolong life, and to use downhole vibration sensors. (Dykstra, et al; EXPERIMENTAL EVALUATIONS OF DRILL STRING DYNAMICS Amoco report Number F94-P-80 1994).’”
30.	Paragraphs [0020] and [0022] form the basis of a submission that the Ma paper should be treated as part of the teaching of this patent, a submission rejected by the Judge and which we consider in detail later.
31.	Following all these “background” matters, the patent then sets out a “Summary of the Invention” which consists of four statements as to what the invention is said to comprise and corresponds to the main claims.   The statements (and claims) go in pairs, each consisting of a method of designing and a roller cone bit.   One pair is concerned with “volume balancing” and the other “force balancing.”    Both at trial and on appeal attention focussed on the main “force balancing” pair of claims, 3 and 6, which we set out here:
“3.	A method of designing a roller cone drill bit comprising a plurality of arms, rotatable cutting structures mounted on respective ones of said arms and a plurality of teeth on each of said cutting structures, the method comprising the steps of: 
(a) calculating the axial force acting on each tooth (18) on each cutting structure (16) of the roller cone drill bit (10);  
(b) calculating the axial force acting on each cutting structure per revolution of the drill bit; 
(c) comparing the axial force acting on each of said cutting structures with the axial force on the other ones of said cutting structures of the bit; 
(d) adjusting at least one geometric parameter on the design of at least one of said cutting structures; and 
(e) repeating steps (a) through (d) until substantially the same axial force will act on each cutting structure when the drill bit (10) is drilling into a formation. 
6. A roller cone drill bit comprising: 
 - three arms;
 - one rotatable cutting structure (16) mounted on each one of said arms; and
 - a plurality of teeth (18) on each of said cutting structures;
wherein the number and locations of said teeth (18) are not identical between ones of said rotatable cutting structures (16); 
characterised in that the axial force on each of said cutting structure is between thirty-one percent and thirty-five percent of the total of the axial force on the bit when the drill bit is drilling into a formation.”
32.	The Judge construed the “formation” of claim 3 to be a simulated formulation (because it had to be) and that of claim 6 to be a real one, see judgment [82-87].   His conclusion is no longer challenged.   Mr Burkill at the closing of his speech suggested that this might have an effect on sufficiency in some way – that even if the product claim 6 were insufficient, somehow claim 3 was not.   This was an entirely new submission not taken below or even in opening the appeal.  Mr Burkill frankly confessed as much.  He also accepted that it was not dealt with separately in the evidence.   Mr Tappin submitted that there was no material difference between the claims, unless claim 3 were directed to a purely fantasy simulation having no resemblance to the real world at all.   We think that would be the wrong way to construe the claim in a context which is all about designing real bits.  Moreover there is a wholly inadequate basis for the point to be taken now when it was not explored in evidence below.   We say no more about it.   The claims stand or fall together.
33.	We turn back to the patent and the Judge’s summary of it:
“[34]	At paragraph [0028] the patent introduces the embodiments to be described with a statement that in those embodiments
‘the roller cone bit designs should have substantially equal mechanical downforce on each of the cones. This is not trivial: without special design consideration, the weight on bit will NOT automatically be equalised among the cones.’
[35]	Three causes of lack of balance are identified in paragraphs [0029]-[0031]. These are respectively (a) asymmetric cutting structures (cones) (b) offset effects and (c) tracking effects. The cones are asymmetric because the teeth (apart from the gage row) are in different places on each cone and are different in number. The gouging and scraping effect of the cone offset (paragraph 10 above) is different from row to row between the cones. Finally, a cone that tracks one of the others will have the effect that at least one cone will be cutting more formation than the other two and the bit is out of balance.
[36]	Paragraph [0032] suggests that substantially equalising the downforce per cone is very important and that this has been discovered by the patentee. Curiously, the words ‘and greatly underestimated’ are added to this assertion of importance, words that in a well-drafted document would tend to suggest that the patentee was here acknowledging that equal downforce on the cones had been recognised as at least one criterion even though its full importance had not been recognised. But this document is so poorly expressed that I am not willing to regard this phrase even as a straw in the wind. The paragraph promises that the application describes bit design procedures that provide optimization of downforce balancing ‘as well as other parameters’.
[37]	The principal advantage of equalising the downforce on the cones is said to lie in the reduction of vibration. Out-of-balance forces parallel to the axis of the hole will create a bending moment rotating about an axis perpendicular to the axis of the hole. This moment may be capable of coupling to the various oscillations of the drill string (paragraph [0034]), so contributing to instability and to uneven wear. The reduction in vibration lies at the root of the improvements in wear performance set out in paragraph [0035]. The improvements for the designer follow from the criterion adopted (equal axial force or equal swept volume) and the use of a simulation system.”
34.	In [38] the Judge notes a cross-reference in [0037] of the patent to the application for the US equivalent to the Orientation Patent.   Before him there was a dispute as to what the cross-reference actually meant and whether the US Patent Application or a similar PCT application could be read as part of the teaching of this patent.  The Judge resolved this against Halliburton at [58-63].  The appeal from this decision is no longer pursued.   
35.	Rather than take the Judge’s summary of the preferred embodiment (which is mixed up with a number of criticisms of it), we set out the description of the “Rock Bit Computer Model” as it appears in the Patent:
[0040] The present invention uses a single element force-cutting relationship in order to develop the total force-cutting relationship of a cone and of an entire roller cone bit. Looking at Figure 1, each tooth, shown on the right side, can be thought of as composed of a collection of elements, such as are shown on the left side. Each element used has a square cross section with area Sc (its cross-section on the x-y plane) and length Le (along the z axis). The force-cutting relationship for this single element may be described by:

where Fze is the normal force and Fxe, Fye are side forces, respectively,  is the compressive strength, Se the cutting depth and  are coefficient associated with formation properties. These coefficients may be determined by lab test. A tooth or an insert can always be divided into several elements. Therefore, the total force on a tooth can be obtained by integrating equation (1) to (3). The single element force model used in the invention has significant advantage over the single tooth or single insert model used in most of the publications. The only way to obtain a force model is by lab test. There are many types of inserts used today for roller cone bit depending on the rock type drilled.  If the single insert force model is used, a lot of tests have to be done and this is very difficult if not impossible. By using the element force model, only a few tests may be enough because any kind of insert or tooth can be always divided into elements. In other words, one element model may be applied to all kinds of inserts or teeth.
[0041] After having the single element force model, the next step is to determine the interaction between inserts and the formation drilled. This step involves the determination of the tooth kinematics (local) from the bit and cone kinematics (global) as described bellow [sic].
(1) The bit kinematics is described by bit rotation speed,  =RPM (revolutions per minute), and the rate of penetration, ROP. Both RPM and ROP may be considered as constant or as function with time.
(2) The cone kinematics is described by cone rotational speed. Each cone may have its own speed. The initial value is calculated from the bit geometric parameters or just estimated from experiment. In the calculation the cone speed may be changed based on the torque acting on the cone. 
(3) At the initial time, t0, the hole bottom is considered as a plane and is meshed into small grids. The tooth is also     meshed into grids (single elements). At any time t, the position of a tooth in space is fully determined. If the tooth is in interaction with the hole bottom, the hole bottom is updated and the cutting depth for each cutting element is calculated and the forces acting on the elements are obtained.
(4) The element forces are integrated into tooth forces, the tooth forces are integrated into cone forces, the cone forces are transferred into bearing forces and the bearing forces are integrated into bit forces.
(5) After the bit is fully drilled into the rock, these forces are recorded at each time step. A period time usually at least 10 seconds is simulated. The average forces may be considered as static forces and are used for evaluation of the balance condition of the cutting structure.”
36.	It is not necessary to go further into the details of the model proposed.   Neither Mr Burkill nor Mr Tappin took us to them.
The alleged insufficiencies
37.	The Judge set these out:
[136]	The insufficiency case as advanced has four aspects, and goes to the heart of the disclosure, since Smith say that the claims in effect require the development of a computer model to carry out the claimed method, and the amount of effort required to develop such a model is clearly undue. The four main heads, and the detailed matters on which Smith rely, are these:
(a)	The skilled reader would be unable to set up the geometrical model of the bit, and in particular the transformations required for the kinematic calculations are inadequately disclosed, the volume matrix V3d0 being difficult to work out and not described;
(b)	The skilled reader would be unable to calculate the forces acting on the teeth, and in particular paragraph [0040] of the specification is misleading and wrong in assuming that force and volume may be equated (equations (1) to (3)) and no method of calculating forces for the purpose of paragraph [0052] is described. The experiments, equipment and data required are not described.
(c)	The skilled reader would be unable to calculate the cone-bit speed ratio, and in particular paragraph [0041] (2) is obscure and may require a calculation nowhere described which is both complex and difficult; and
(d)	The section of the specification entitled ‘Design of a Force Balanced Roller Cone Bit’ contains such inaccuracies and omissions as would prevent the skilled reader from designing a bit by following the instructions provided.
38.	The Judge found the patent to be insufficient in respect of all four heads.   Mr Tappin told us that the Comptroller could not support that part of head (a) about the volume matrix (dealt with by the Judge at [148]).   Mr Burkill had explained how the Judge’s assumption that a working simulation cannot be constructed without the volume matrix was an error and Mr Tappin agreed.   It is not necessary to go further into this point.   The main argument focussed on the other objections.
Outline of Halliburton’s case
39.	The thrust of Halliburton’s case is this:  that the “big idea” disclosed by the patent is this:
i)	The motion of the cones and teeth can and should be modelled mathematically. 
ii)	The forces acting on the bit and its components, and the trajectories of the teeth through the rock, should also be modelled.
iii)	The downwards forces on each cone should be balanced as between the cones.
iv)	This should be done by calculating the forces on each tooth and thus on each cone, and adjusting the design and recalculating those forces until such balance is achieved.  
40.	Halliburton go on to say that the “big idea” has been found to be novel and non-obvious – inventive.   Moreover implementation of that idea is essentially a matter of producing a usable computer simulation which, although not perfectly accurate (no computer simulation can ever be so) is sufficiently accurate for practical purposes or at least is not shown to be so inaccurate as to be useless.
41.	Halliburton do not go so far as to say that the notional skilled person/team, given the “big idea” and no more, would be able, using no more than ordinary skill and knowledge, to implement the idea.   On the contrary, it was accepted that more teaching is needed.  Halliburton say that that teaching is provided by either the detailed description in the patent of the preferred embodiment or by the fact that the teaching of the patent should be taken to include the Ma paper referred to in [0020].   
The sufficiency of the specific description
42.	Mr Burkill suggested that the skilled man would go to Ma first.  Only if his case about the cross-reference failed was it necessary for him to “fall back” (Mr Burkill’s expression) on the specific description.  That cannot be correct.   The first place the notional (or indeed any actual) reader would go for the teaching as to how to perform the invention is surely the patent itself.   And that is particularly so in the case of this patent which says that its method is superior to anything in the prior art: “The single element force model used in the invention has significant advantage over the single tooth or single insert model used in most of the publications.”
(a) A kinematic model?
43.	So we start where we think the skilled person/team would start, with the specific and preferred embodiment.   The first question is whether or not there is enough information to construct a kinematic model of the bit – a model not merely showing what the bit looks like in three dimensions but how the various components move in relation to each other.  For it must be remembered that each of the cones is not merely offset, but is caused to rotate by a combination of rolling friction, gouging and scraping.
44.	The Judge held that too much work was involved, even at this point.   He said:
“[145]	Mr Hall accepted that this was ‘a lot of work’. Even if it were legitimate to look at the Ma book, which is not shown to be common general knowledge, this evidence would support a suggestion of insufficiency. Without the Ma book not enough is disclosed, and it was not suggested that the Ma paper helped in this respect. As I have indicated, I feel uneasy with the allegation of insufficiency based on geometric and kinematic considerations alone, but in the end I think that the balance of the evidence tips in favour of a conclusion of insufficiency.”
45.	The reference to the “Ma book” is to a book which contains what Ma describes as “the Fundamental Equations of the modern geometry of Rock bit.”   Professor Newland said:
“The problem is what this [i.e. ordinary CAD] software cannot do is simulate the motion of the cones and the drill bit simultaneously in such a way that the trajectory of the teeth can be followed without having the appropriate sub-program which would enable equations like the equations in chapter 2 of Ma.” (Transcript p.850)
And, when pressed:
“What I am saying is that these are equations which are difficult to derive, and they are complicated, and they include a lot of variables and angles and you have to go through that agony in order to be able to say where the teeth are and reference to the formation.  Whatever method of calculation you use, in effect, you come down to those equations.” (p.851-2).
46.	A little later the Professor pointed out that Ma had first published these equations in a paper.  He said:
“Ma is using these equations [i.e. those in the book] which he had published some 10 years earlier in a paper to the American Society of Mechanical Engineers with his Professor J.J. Azar when he worked as a research fellow in the United States at the University of Tulsa.  That was a refereed paper -- you can see that from the credentials of the paper and the dates of receipt and publication -- of the ASME and that was regarded at the time as a major step forward in understanding the dynamics of these drill bits.  If it had not been, it would not have been published and nor would Azar have been associated with it.  That is what Ma is quoting here.  All I am saying is that is a difficult and big calculation. It merited a scientific paper when it was done and it remains a significant feat of 3-D geometry for an engineer.” (p.853).
47.	The Judge made a minor and irrelevant error in saying the Ma paper (as opposed to book) could not have helped, for it too contains the relevant equations.  This does not matter.  For, given that neither the Ma paper or book forms part of the common general knowledge (as was accepted), the effect of the Professor’s evidence is that the skilled team would in effect have to go through all that Ma had done on the way to implementing the invention.   
48.	And on top of that more would be involved:
“Even if I took the equations straight out of Ma's book, it would still be a significant project because you have got to understand all the aspects of them and get the correct numbers into them and model this.  Following all those points on every tooth, into           contact with the ground and out of contact with the ground, is just a huge task.” (Professor Newland at transcript p.864)
49.	Given that evidence, we cannot see any error, still less any error of principle, in the Judge’s decision on this point.  He was fully conscious of the fact that computer related inventions inherently are apt to involve a lot of work (see the Judgment at [133] quoted above).  Here he had evidence that an extraordinary amount of work would be involved, work which would be “agony”, work which in part would be enough to justify publication in a peer-reviewed scientific publication.   That seems ample enough material for him to decide that the invention was not disclosed clearly and completely enough for it to be performed by a person skilled in the art.
50.	It may be noted that this aspect of insufficiency is right at the heart of Professor Newland’s expertise.   Mr Burkill’s submission, about the fact that he had no experience of rock bit design, is simply irrelevant here.  Mr Burkill suggested that the Professor was not willing to consider collaboration with an experienced rock bit designer such as Mr Hall.  For this Mr Burkill relied on the Professor’s answer that he would regard it as plagiarism if one of his students, asked to build a computer model, went to a rock bit designer for help.   That answer is fair in its context.   But what really matters is that if the student had indeed gone to the rock bit designer, the latter would not have been able to help.  Ma’s equations were not part of the common general knowledge and the student would have come away empty-handed.
51.	Mr Burkill’s only other point here was that the degree of work was irrelevant in law.  For the reasons given above we think this submission is fallacious.
(b) bit/cone speed ratio?
52.	We turn to the next aspect of alleged insufficiency:  the problem about the bit/cone speed.   As the bit rotates, so do the cones.   But the cones have offset axes of rotation and differ from each other in shape and in the disposition of their teeth.  Although driven by the bit rotation, there is no obvious or automatic relationship between the bit speed and the cone speed:  a fixed cone-bit speed ratio that derives from a non-slip rolling assumption is not necessarily appropriate.  Yet, to balance the upward forces on the cones, you need to know the positions of the cones and especially of their teeth.  Since the upforce on each cone is the sum of the vertical components of force on the teeth in contact with the ground you need a model which gets the teeth in the right place.   So you need to know the speed of rotation of each cone.   If you make even a small error in the bit/cone speed, the error will accumulate with successive rotations of the bit.   All the patent says about cone speed is in [0041] which we have already quoted in full.  The short passage reads:
“Each cone may have its own speed. The initial value is calculated from the bit geometric parameters or just estimated from experiment. In the calculation the cone speed may be changed based on the torque acting on the cone.”
53.	Mr Burkill submitted that the Judge misconstrued the last sentence of this, that it meant either you can change the cone speed based on torque or not at all, rather than you can change the cone speed based on torque or in some other unspecified way.   We do not think it matters.   The Judge made a clear finding that an accurate cone/bit speed ratio is essential.   There are virtually no instructions as to how this is to be achieved.  And Mr Hall’s evidence (Judgment [160-162]) about its importance and how when he was at Hughes “we could never come up with an accurate cone speed to bit ratio” provides ample material to justify those findings.
54.	Mr Burkill submitted that even if accuracy could not be achieved, it was not shown to matter.   After all, he submitted, everyone knew that perfection in modeling could not be achieved.   He suggested that it might not matter because any error for one cone might have corresponding errors for the others and the overall resultant balancing of forces could be achieved.   
55.	We agree with neither point.   We of course accept that no-one can produce perfect computer models.  But when one has an error which is cumulative, it is obvious that the model will, after a short time, bear no resemblance to the reality it is supposed to emulate.   All the teeth will be in the wrong place. At the very least the burden has shifted to show that something which was “very important” (to use Mr Hall’s words) does not in fact matter at all for a practical result.
56.	As to the averaging point, there is simply no evidence to support it and it was not advanced to the Judge.  It seems inherently wrong given that the cones will probably rotate at different speeds.
(c)  A force model?
57.	We come to the last insufficiency of the “preferred embodiment”, the force modeling.   Equation (1) contains the basic assumption for the proposed computer model.  A tooth of a bit is thought of as a bundle of “matchsticks” or (using Prof. Limebeer’s analogy) as the bristles of a brush.   Each matchstick or bristle is then assumed to penetrate the rock as an independent element.  The three formulae are intended to be for the calculation of the normal and sideways forces acting on the element.   The sideways forces are dependent on the normal force Fze.   So it is equation (1) which is the basis for the model.   All else flows from it.   
58.	Now there is an initial obscurity about it.  For the patent, having defined Sc as the cross-section area, never mentions this parameter again.  Yet it clearly is very important:  the greater the cross-section of the element the more force you will need for it to penetrate the rock.   The answer here is that ke, said to be “a coefficient associated with formation properties”, must also depend on Sc.  As a piece of scientific writing this is hardly helpful.  But, since it was not the basis of the insufficiency found, we say no more.
59.	The basic assumption in equation (1) is that force is linearly proportional to depth of penetration, Se.   This is confirmed by the patent at  [0046] which says:
“According to equation (1) the force acting on an element is proportional to the rock volume removed by that element”.
Actually equation (1) does not mention rock volume.  But since rock volume removed will also be linearly proportional to depth, Sc, one can see that this sentence confirms that an assumption of linearity has been made.
60.	Professor Newland doubted the validity of equation (1).   To show that his doubts were unjustified, a paper by Maurer was put to him.  It was about experimental measurements of force versus depth of penetration of a chisel- shaped tooth and showed a linear relationship. Professor Newland demonstrated that an elemental force law that is linear with the depth of penetration would necessarily produce a whole-chisel force law which is quadratic as to the depth of penetration, Se.  As a result  equation (1) was held wrong by the Judge:
“Equation (1) is just wrong.  It was not established that the skilled man would appreciate that this error existed, let alone that it was obvious.” [152]
And:
“If, as I consider a fair reading of the specification indicates, these equations are intended to provide a guide for the construction of the model, the model is wrong and cannot give useful results.” [153]
61.	We consider this conclusion of fact to be entirely unimpeachable.   Mr Burkill suggested the conclusion “no useful results” was not proved to be so.   He pointed out that in reality rock is brittle and will be penetrated by a series of breaks with the force on a tooth building up to a fracture, dropping off and building up again to the next fracture. Yet Mr Hall was prepared to accept equation (1)’s assumption of linearity as good enough to give a useful result.    Maybe, Mr Burkill postulated, a linear assumption could give useful results even if it was wrong in principle.  And, he said, the burden of proof lay on Smith to show the model was so imperfect as to be useless.  They had not taken that final step.
62.	We regard that as clutching at straws.   Once the fundamental assumption for the modeling is shown to be wrong, one would expect the model so based to be useless.  If garbage is put in, you would expect it to come out:  the evidential onus must lie on anyone who wants to show otherwise.   
63.	Overall, therefore, on the specific embodiment, the position is this:  that the patent requires work going beyond the “agony” of the work required to produce an original scientific paper worthy of publication after peer review, sets the impossible but “very important” task of calculating the bit/cone speed ratio, and is founded on a wrong assumption about the relationship between depth of penetration and force.    It is hardly surprising the Judge found it insufficient.
A cross-reference to the Ma Paper for Sufficiency?
64.	Nor is it surprising that Mr Burkill’s first attack on the finding of insufficiency was not to try to justify the sufficiency of the specific embodiment but to try to show that the Ma paper should be regarded as part of the teaching of the patent.   The passage said to do this is [0020] and [0022] of the Patent which we have included in our quotations from the judgment above.
65.	What the judge said, having quoted [0022] is this:
“[30]	This passage seems to me to carry on the discussion in paragraph [0020] of the Ma paper, which is concerned with the modelling of the bottom hole pattern, and it is dismissive in tone, suggesting that Ma’s program can be used only to predict the presence of obvious problems such as tracking. Halliburton contend that the disclosure of the Ma paper, which is rather more comprehensive than paragraphs [0020] and [0022] suggest, is incorporated by reference. The words used are not, in my judgment, capable of incorporating this disclosure into the disclosure of the patent. Patent specifications should be complete in themselves and while they must be read like any other document these words do no more than dismiss the Ma paper (and the other citations) as ineffective components of the state of the art.”
And:
“[60]	The reference to the Ma paper is summarised in paragraph 29 above. As a matter of construction, this is the thinnest possible basis for a suggestion that the disclosure of the paper is to be incorporated in the patent. It seems to me that the specification does not point the addressee in the direction of the Ma paper for the purpose of supplementing its disclosure for any purpose. It is a description of the background prior art. I think that the Ma paper is really disclosed as a record of the existence of a computer program which does not do what the claim requires, in other words a failed proposal. If the patentee had wished to use the disclosure of Ma, the cross-reference should have been express. 
[61]	In general, cross-referencing for the purpose of supplementing the disclosure is highly undesirable, and is not permitted by the EPO, which deals with the matter as follows in its Guidelines for examination Chapter C-II:
‘4.18 Reference documents 
References in European patent applications to other documents may relate either to the background art or to part of the disclosure of the invention.
Where the reference document relates to the background art, it may be in the application as originally filed or introduced at a later date (see II, 4.3 and 4.4).
Where the reference document relates directly to the disclosure of the invention (e.g. details of one of the components of a claimed apparatus), then the examiner should first consider whether knowing what is in the reference document is in fact essential for carrying out the invention as meant by Art. 83: 
If not essential, the usual expression "which is hereby incorporated by reference", or any expression of the same kind, should be deleted from the description.
If matter in the document referred to is essential to satisfy the requirements of Art. 83, the examiner should require the deletion of the above-mentioned expression and that, instead, the matter is expressly incorporated into the description, because the patent specification should, regarding the essential features of the invention, be self-contained, i.e. capable of being understood without reference to any other document. One should also bear in mind that reference documents are not part of the text to be translated pursuant to Art. 65.’
[62]	I am not concerned with how an application is to be examined, but this principle is a sound one. If the disclosure is essential to the patent that fact should be made abundantly clear. As a matter of the ordinary principles of document construction it is not permissible to exclude the possibility of a cross-reference for essential material: but the court must, I think, be on its guard to ensure that the cross-reference is a proper one. This is not such a cross-reference.
66.	Mr Burkill says the judge was unfair.  Neither [0020] nor [0022] of the Patent is “dismissive in tone”:  they in effect state what Ma had done but that Ma had not realized that his work could be put to use for bit design, other than for obvious purposes.  Once the skilled person/team was given the “big idea” of force balancing by the patent he would realize that the Ma paper could provide the basis of a programme which he could use for bit design to achieve that object.
67.	We reject that argument.   A patent is supposed to teach people how to perform the invention.   If necessary information is not actually in the patent, then the skilled person must be given a clear unambiguous direction of where to get it.   He cannot be expected to find such a direction buried in acknowledgements of the prior art.   Ultimately the question is one of construction – does the patent clearly teach the skilled addressee how to perform the invention?
68.	Turning to this patent more specifically, there are a host of reasons why Ma cannot be regarded as part of its description as to how to perform its invention:
a)	First and most obviously it simply does not say that.
b)	The patent puts forward its element method as superior to “single tooth or single insert models used in most of the publications.”   Faced with abject failure by reason of impossibility on the patentee’s specific proposal, why should the skilled addressee expect, buried in the acknowledgement of the prior art, anything useful for implementation of the invention?  Indeed if he did go to Ma he would find it to be a single tooth model, said by the patentee to be inferior.
c)	The actual reference comes under the heading:  “Background: Bottom Hole Analysis” which is not an indication that Ma is relevant to bit design.
d)	There is no suggestion in the passage that the Ma paper contains a force model.    So why would the skilled addressee expect to find one there at all, still less one that might be adapted for force balancing?
e)	The very presentation of the invention is not consistent with the notion that you can use existing methods of calculation but with the difference that you aim to force balance – just add the “big idea” to known techniques.  The whole method is presented as new in itself, as for instance in [0025] where the steps of claim 3 are set out as a completely new calculation.
f)	The patent actually goes out of its way, in [0057] to identify three publications of which it says “all of which are hereby incorporated by reference”.   The Ma paper is not one of them.  If the author wanted the reader to understand that Ma was also incorporated by reference, this was surely a place to do it.
69.	So we think the Judge was entirely right to say that the Ma paper is not included by reference.   We would add that even if it were, Halliburton would find difficulties based on the evidence of their own witness, Mr Hall.  For he was of the opinion that the paper did not assist with the bit/cone speed ratio problem, the “very important” (his words) problem to be solved to prevent the divergent model going wildly wrong.
70.	That really concludes this appeal.  It is not necessary to go into some other points, such as the availability of suitable equipment for testing rock to get the relevant coefficients.
Other points
71.	But we should add a few words about some other matters.  First there was Mr Burkill’s submission that the Judge in effect gave Professor Newland, who had no experience of rock drill design, more weight than the experienced Mr Hall.   We have already dealt with it in part, in relation to the kinematic model.   But there is more to be said:
a)	In the key areas to which we have referred above, the Professor’s evidence (as an engineer and computer modeler) is the relevant evidence – that was not Mr Hall’s expertise.
b)	As regard the bit/cone speed ratio problem, the judge particularly relied on Mr Hall’s evidence.
c)	Mr Hall had given unsatisfactory evidence in a number of respects (for the details see the judgment at [151], [179] and [195]). 
d)	The Judge was very alive to the point and weighed it carefully:
“[166]	The last objection that Halliburton make to this formidable case on insufficiency depends upon the contrast they draw between the wide experience of Mr Hall on the one hand and Professor Newland’s lack of specific experience in the industry on the other. It was submitted that Professor Newland’s lack of experience deprives his evidence of much weight when it is set against that of Mr Hall. I reject this submission. I have already indicated that in a number of respects Mr Hall’s evidence was not consistent. No aspect of the insufficiencies that I find established depends upon a close knowledge of the drilling industry or of the manufacture of drills. They are, on the contrary, really objections based upon the difficulty of constructing a model given the data and other information made available by the specification. The objections of insufficiency that I have set out in paragraph 136 above are all established.”
72.	It is quite impossible to spell out any error here, still less one of principle.
73.	Next there was Mr Burkill’s reliance on Smith’s own patent.  It was suggested that this gave no or little more information than the patent in suit, showing that those in the industry thought it was enough.  We are not sure that is entirely fair (e.g. there is, in Smith’s patent, probably a fair cross-reference incorporating the Ma paper and we are not aware that it has any fundamental blunders such as the false assumption about the force/depth relationship) but it does not matter.   This case has to be decided in relation to the evidence.  Whether Smith’s patent is or is not sufficient is irrelevant.
74.	Mr Burkill also relied upon some Smith advertising in which they extol the virtues of their program for bit design, saying it achieves force balancing.   He suggested this justified his “big idea” approach and also, perhaps, was some evidence of sufficiency in that Smith claimed they had achieved a useful force balancing computer program.   But neither point goes to the sufficiency of the patent in suit and counts for nothing against the detailed evidence as to this.
75.	Likewise we do not think the fact that Halliburton themselves led no evidence about their own implementation (if any) of their idea matters when matched against the detailed evidence.   Whether they tried and failed, or thought the work too much, or did not implement it for other reasons are matters of mere conjecture.
76.	Finally there is the question of permission to appeal certain of the facts.   Two aspects of these remained live at the commencement of this appeal, that relating to the volume matrix point and that relating to calculation of forces on the tooth.  In respect of the first of these, as we have said, the Comptroller indicated that the Judge had indeed made an error, so it would be right formally to grant permission to appeal.  However, now that we have understood the point in relation to the latter, we are quite sure that the Judge got it right and that formally there is no realistic prospect of appeal.   So formally, although we have gone into the point in detail, we refuse permission to appeal.