England and Wales High Court (Patents Court) Decisions

IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT

		21 July 2000

Mr Justice Pumfrey:

Introduction

1. This is an action for infringement of EP (UK) 0297110 of which the claimant, hereinafter 'Kimberly-Clark', is the registered proprietor. The title of the invention is 'Absorbent Material', but the patent as granted relates to diapers (nappies), incontinence aids and the like. The alleged infringement is a baby's nappy placed on the market by the defendants, to whom I shall refer as 'P&G'.
2. The patentee seeks to amend the patent. As a result of a decision of the Court of Appeal, the issues affecting the exercise of the discretion to permit amendment of the patent were investigated at trial. The purpose of the amendment is to limit the scope of the claim to children's' nappies and, apart from the discretionary issues, the defendants say that the amendments are objectionable on statutory grounds.
3. The allegation is that the Pampers nappies manufactured by P&G infringe the claim since they incorporate a layer of material which satisfies a test (the "PRD test") set out in the specification. The only test of the allegedly infringing nappies was carried out by Kimberly-Clark and there are no experiments in reply. There are said to be two objections to the experimental technique which was used. These objections lead to an allegation of insufficiency. These important issues aside, the attack on the patent in the end came down to an allegation of obviousness against the amended claim, it being conceded that unamended claim 1 was invalid. The obviousness argument was developed in the light of three prior publications referred to as Meyer, Depend and 'Example Nine', seen against the background of the common general knowledge.

Background

4. At the priority date of the patent in suit, which is accepted for these purposes as having been the 8th May 1989, there were a large number of different adult incontinence products and disposable diapers on the market. The general principles of construction appear to have been well established. There were certain differences in detail between adult incontinence products and those made for children, mainly relating to the shape of the product and the manner in which the diaper is fastened and sealed around the leg, but there is undoubtedly a basic structure common to all these products. So far as children's nappies are concerned, the 'Baby Diaper Design Update 1987' published by Marketing/Technology Service Inc is a survey of all the products available in the market and covers the United States, Europe and Japan.
5. The function of a disposable nappy is to absorb and retain urine. The nappy should be capable of retaining not one but several doses of urine delivered at intervals. In the art it would seem that such successive doses of urine are referred to as successive 'insults' and this is the way they were referred to at trial. The structure of the nappy is simply described: it consists of an impermeable back sheet, absorbent layers and a top sheet which is liquid permeable and is intended to be in contact with the skin of the user. The questions with which I am concerned relate to the nature of the absorbent layers.
6. At the priority date, the commonest absorbent was what is referred to as cellulosic fluff or fluff pulp. This material is highly absorbent and highly hydrophilic. It was well known that the problem with a nappy core which consists of fluff pulp only is that when it is wetted the bulky structure of the fluff collapses so reducing its retaining power and its ability to accommodate a second load. It is a matter, perhaps, of no great insight to appreciate that all the urine dose is delivered to a comparatively small area of the nappy. To help minimise local saturation and pooling, and also to utilise all the absorbent material present in the nappy, it had been appreciated by 1987 that it was a good idea to use layers of material which would assist in 'wicking' the urine away from its point of delivery. A good wicking material does not necessarily have the same qualities as a good absorbent material. Finally, there was a market pressure, or perhaps marketing desire, to make the nappy as thin as possible. This had led by 1987 to the investigation and use of non-fibrous absorbent materials. The materials used, referred to as super absorbent materials ("SAM") were particles of activated silica gel dispersed in the fibrous absorbent layers. These materials have particular properties which must be accommodated in the design of the disposable nappy. While they are highly absorbent and do not collapse, they are comparatively slow to absorb liquid and as they do so they swell. It was recognised in 1987 that one of the consequences of swelling was to block up the fibrous structure of the remaining material, which results in pooling, slow absorption and other undesirable effects.
7. The MTS report summarises the function of the layers in a disposable diaper as follows:

"Many diaper core designs include layers of different materials. These can include nonwoven webs, carrier tissue used to move pulp through the machine, superabsorbents, synthetic fibers and wood fluff pulp pads, as well as combinations. Japanese diapers often include several layers of different materials, some of which are quite exotic and no doubt expensive. Layers are meant to improve diaper performance in ways such as increasing its ability to spread liquid, containing liquid, separating liquid from the baby's skin, etc.

Obviously layers incorporating different material will perform differently in absorption and spreading and wicking. A layer of hydrophobic synthetic fibers located between the facing and fluff pad will allow liquid to penetrate through to the absorbent pad, but also will help to prevent the facing from contacting the liquid again once absorbed.

A dense layer or pile of super absorbent granules will tend to block liquid movement within the SA layer. As the SA absorbs liquid it also swells physically and contains the liquid, while preventing other liquid from moving because swelling blocks the capillary structure. This phenomenon referred to as 'gel blocking'. For example, if this layer were located between the facing and the fluff pad for instance, it would tend to inhibit liquid movement away from the point of application as the liquid must penetrate the layering of obstructing SA gel to get to the fluff pulp. Any design of this type would be disastrous.

High purity fluff pulps absorb liquid at a fast rate and have the ability to spread the liquid to other areas of the product away from the point of application. This is caused by the capillary action of a fluff pad. It is generally true that as the density of a pad increases (bulk decreases) the ability to spread the liquid faster and further from the point of application increases. The problem associated with fluff pulp - only cores is that when it encounters a load the structure collapses, resulting in a loss of liquid. Therefore it is desired to incorporate superabsorbents in the fluff or have them layered separately in order to increase liquid retention of the absorbent structure under load while still retaining good wicking and initial absorbency".

8. Both Dr Creagan who gave evidence for Kimberly-Clark and Mr Moran, who gave evidence for P&G, accepted that this passage reflected the basic understanding of the skilled man at the priority date.
9. I should say a word about the skilled man to whom this specification is addressed. There seems to be no doubt that the design of these ordinary domestic items involves contributions from a number of sources. There are materials scientists, who are concerned with the properties of the materials used in the layers, production engineers, who are concerned who with the ease of the production of any given design at the very high production rates may be required, and designers whose task it is to balance the considerations of the type to which the passage I have quoted above refers. Dr Creagan was an employee of Kimberly-Clark and a materials scientist. Mr Moran on the other hand was somebody who had a wide knowledge of different designs of diaper, without himself having designed: he was a repository of design information. He was an employee of P&G. The witnesses who gave evidence in relation to the test in the specification, Mr Courtray and Dr Abbott, while not employees of the parties, were familiar with the parties and with testing techniques in this field. All the witnesses gave their evidence fairly, and with a view to assisting me. While reflecting their experience of different parts of the input to the design of a nappy, their evidence was helpful.
10. It will be apparent from the brief summary of the design considerations which I have given above that a basic and obvious construction for diapers as of 1987 would be an impermeable backing sheet, a layer of fluff pulp or other hydrophilic material interspersed with super absorbent gel particles, a layer intended to separate the absorbing layer from the cover sheet and the cover sheet itself. Thereafter, the freedom given to the designer is a wide one. The MTS report says this:

"Remember that it is important to understand the interaction of shape and materials, as well as to consider the many additional aspects of product design which contribute to success or failure, including:

- Amount of absorbent material

- Where it is and how it is contoured

- Uniformity and density of the absorbent core

- Initial absorbency characteristics of the core

- Swelling or collapse of the absorbent core

- Amount, type (speed) and location of superabsorbents and fluff

- Retention and collapse of the absorbent core under pressure

- Cover stock and wicking layer interactions

- Fastening system efficiency

- Spreading and wicking

- Shape of the product

- Changes in shape when wet

- Fitting characteristics (the most important of all variables)

There are several variations used in thin structures, including layering the web with discrete SA locations and special wicking webs. Of course, proper control of density and surface chemistry of the fibers, in addition to chemistry, surface area and physical form of the superabsorbent, has a major effect on wicking and fluid transport.

Superabsorbent positioning within the fluff pad is an important design variable. ...it is possible to position the superabsorbent in nearly any part of the pad at nearly any weight and concentration. P&G and K-C use homogeneous distribution of SA and pulp in the U.S. Since SA holds onto liquid, where the SA is located towards the top of the fluff pad the rewet characteristics will improve. As the SA is located further from the top of the pad, the rewet generally increases. Homogeneously blended SA and wood pulp fluff pads have good rewet characteristics as shown below."

11. I conclude that at the priority date the basic requirements for a diaper were well understood. So also were the functions of the various layers which it might be desired to incorporate within the design. With this introduction I can turn to the patent in suit.

The patent in suit

12. Before amendment, the invention of the patent in suit was said to relate to 'personal care products' which includes diapers for adults and babies and disposable sanitary pads. For the reasons which I give when I consider the issues relating to amendment, I consider that the amendments sought are formally allowable and should not be refused as a matter of discretion. Accordingly, my discussion of the specification deals with the document as sought to be amended.
13. It is pointed out that the desired performance objectives of such products include 'low leakage from the product and a dry feel to the wearer' and that the products commonly fail before the total absorbent capacity of the product is utilised. The specification discusses physical methods of preventing leakage such as elastic leg gathers and other methods such as increasing the amount and configuration of the absorbent material at the zone of the diaper at which what are called 'liquid surges' typically occur. After reference to a number of publications, the problem which the invention is alleged to overcome is identified in these words:

"Despite the development of absorbent structures of the types surveyed above, there remains a need for improved absorbent diapers which can adequately reduce the instance of leakage. There is a need for an absorbent structure which can provide improved handling of liquid surges and more effectively uptake and retain repeated loading of liquid during use.'

The advantages of the structure according to Claim 1 as amended are described as follows:

"The absorbent structure of the present invention advantageously provides a surge management portion which can rapidly uptake body exudates and can maintain the rate of uptake even after the absorbent structure has been previously wetted with one or more liquid insults. The invention can also provide a transitional, limited-time reservoir for temporarily containing each liquid surge occurring in the target zone of the absorbent structure, and can further provide a more complete release and movement of the liquid into the retention portion of the structure. As a result, a diaper which includes the distinctive absorbent structure of the present invention can help avoid puddling liquid against the wearer's skin, and more rapidly move the liquid away from the skin and into the absorbent structure. The transitional reservoir function of the invention can advantageously allow the retention portion a greater period of time in which to accept repeated surges of liquid while also isolating the liquid away from the wear's skin. The more complete release of the liquid into the retention portion helps to maintain a drier section of the diaper against the wearer. Thus the distinctive structure of the present invention can reduce the amount of liquid held against the wear's skin, reduce leakage of liquid from the absorbent structure, and provide improved dryness and comfort to the wearer. In addition, the distinctive aspects of the present invention can be advantageously sustained during the course of multiple insults of liquid delivered into the absorbent structure."

14. The basic idea therefore is to provide a part of the nappy at the target zone which has two functions. The first function is to absorb the liquid rapidly, and the second function is to distribute the liquid into the absorbent structure. On the hypothesis that the distribution function is slower than the rapid take-up (which is why the layer is proposed at all) it can be seen that the layer fulfils a holding function. The fact that the layer will give up liquid to the absorbing part of the structure means that its hold on the liquid is less than that of the absorbent structure and it will feel dryer against the skin. Translated into the details of nappy construction, the basic idea of the invention is thus a two layer structure in which a 'surge management' layer overlies an absorbent layer. The absorbent layer is, as the passage on page 7 line 21 makes clear, a hydrophilic layer containing SAM at the user's option. While the materials of the surge management portion are not defined, its function is described on page 8 line 35 as follows:

"The surge management portion 46 should have a operable level of density and basis weight to quickly collect and temporarily hold liquid surges, and to transport the liquid from the initial entrance point to other parts of the absorbent structure 32, particularly the retention portion 48. This configuration helps prevent the liquid from pooling and collecting on the top sheet 28, thereby reducing the feeling of wetness by the wearer."

The balance of materials needed to achieve this effect is described at page 9line 35:

"It has been found that an effective fabric for constructing the surge management portion can be distinctively characterized by some or all of the following qualities: (a) a resilient structure having a selected basis weight; (b) an appropriate amount of total fibre-surface-area within the internal structure of the fabric; (c) a balance of fibre-surface-areas which are wettable and non wettable; and (d) an appropriate distribution of the fibres within the volumetric space defined by the surge management portion. More particularly, the surge management portion can incorporate distinctive parameters which help characterise the liquid capillarity and other features of surge management portion 46. The parameters include the total amount of fibre-surface-area per standard unit of fabric; the amount of wettable surface-area of such fibres per standard unit of fabric; a total-wettable-surface-area multiplied-by-density parameter; and total-non wettable-surface-area-multiplied-by-density parameter."

15. The functional features of the layer are defined as an ability to stay open under load, to maintain void volume in the fabric; to resist collapsing when wetted the better to release liquid and to allow the fabric to be desorbed; and to be regenerating after being wetted to preserve the void volume for successive insults. The specification thereafter concentrates upon the features of the surge management layer. Its basis weight (that is, the unit weight expressed as grams per square metre, or gsm) is said to be at least 60 gsm and preferably at least about 90 gsm. The preferable range of basis weights is said to be between 90 and 3000 gsm. The basis weight is said to be important for providing a total holding capacity adequate temporarily to retain the amount of liquid typically discharged by a wearer. The transport properties of the layer are described as depending upon the surface areas of the fibres, and so it is said that the layer is made up of wettable and non wettable fibres, 'properly selected' so as to give fluid access to the void volume of the material without adversely effecting the fluid release characteristics. Particular values of the fibre surface area of the wettable and the non wettable fibres form the subject matter of certain of the claims of the patent, but I was not concerned with these claims and no evidence was directed to them.
16. The specification provides a test which is said to allow the testing and screening of fabrics to determine 'whether the structures thereof provide required values for particular surge management parameters'. Correct performance in this test of the material used as the surge management means of a diaper is essential to a finding of infringement, since the test is incorporated in claim 1 of the patent. It is the subject of the principal allegations of insufficiency. I have therefore to consider it in some detail. The test is said also to provide for testing individual fabrics whereby the performance of the fabrics themselves can be measured without variables being introduced by other components of the completed diaper. This test is called the penetration rate desorption or 'PRD' test.
17. The PRD test has two stages. In summary, the material under test is soaked with synthetic urine in a controlled way. It is then "desorbed" by compressing it against a "desorption pad" which is required to possess certain stated properties, for which a further test is prescribed.
18. The apparatus upon which the first stage of the test (soaking) is to be conducted is shown in figures 14 and 15 of the specification. Figure 14 shows the apparatus in an exploded view. The sample 126 lies on a 'plastic screen' 124 which is itself supported upon projections from the wall of the transparent cylindrical tube 112. In the preferred embodiment this tube is three inches in inner diameter. Beneath the plastic are drilled holes 118 which are said to allow air circulation to the inside of the tube. This apparatus is used solely for the purpose of subjecting the test sample to a standard test amount of synthetic urine at a volume rate of 15 ml per second. In use, the sample is placed upon the plastic screen, and subjected to the flow of synthetic urine. The time required for all liquid to penetrate the surface of the sample is measured in seconds. Obviously most of the liquid will pass straight through the sample, but some will be retained. The sample with the retained liquid is removed from the apparatus and weighed.
19. The next stage of the process is what gave rise to the controversy. It is perhaps best to quote the words of the specification:

"The sample 126 is then placed on a 10.16cm by 10.16cm (4? by 4?) square desorption pad composed of cellulosic wood pulp fluff mixed with superabsorbent particles. To this purpose, the desorption pad can comprise a mixture of softwood fluff designated 'CR-54' available from Kimberly-Clark Corporation, and a hardwood pulp fluff designated 'Longlac 19®' also available from Kimberly -Clark Corporation which have been air-laid according to conventional techniques to form a fibrous web. About 12% of the dry weight of the desorption pad comprises superabsorbent particles available from Hoechst-Celanese Corporation as IM 1500. The particles are mixed with the air-laid fluff fibres to form a pad having a density of about 0.1 g/cm³ and a basis weight of about 1400 g/m². The desorption pad should be constructed and arranged such that after an immersed saturation with synthetic urine under free-swell conditions for 5 min, the pad retains at least 10 g of synthetic urine per gram of desorption pad after being subjected to an air pressure differential (vacuum suction) of about 3.45 kPa (about 0.5 psi) applied across the thickness of the pad for 5 min. A suitable weight (not shown) is then placed on the fabric sample 126 to apply a pressure of 1.72369 kPa (0.25 psi) over the entire sample to desorb the liquid from sample 126 and into the desorption pad positioned immediately below the sample. After 15 minutes, the weight is removed and the sample 126 is weighed again. This completes the first cycle. The desorption pad is discarded and a fresh desorption pad is obtained for the next cycle of the procedure. The sample is then returned to supporting screen 124 substantially without further drying or desorption of the sample, and the testing cycle (introducing liquid, weighing, desorbing and weighing) is repeated two more times for a total of three cycles. The three uptake-and-desorption cycles are completed within a period of 60 minutes."

20. This passage describes both the test which is to be carried out on the sample and the test to be carried out on the desorption pad. It is the latter test which is said to be insufficiently described. Assuming that the right desorption pads can be obtained, the soaking and desorption cycle is performed three times on the test sample, using a fresh desorption pad on each occasion. The values which are obtained are the uptake time (the time for all the urine in the first part of the test to penetrate the fabric-most will pass straight through), the "temporary loading value" which is the ratio of the weight of urine retained to the weight of the fabric (also derived from the first part of the test) and the residual value, which is the ratio of the weight of urine retained after desorption to the weight of the fabric. These values are said to be indicators of the liquid uptake rate, the transitional reservoir capacity and the release characteristics of the sample. The ideal is to have a short uptake time, a high temporary loading value and a low residual value.
21. Having explained how to measure the uptake time and the weight of residual urine after desorption per gram of fabric the specification proceeds to describe how to use the results to alter the material of the surge management portion by changing the wettable-fibre-surface-area and/or changing the density or the bulk fabric so as to change the relative proportions of wettable and non wettable fibres within the fabric material. The specification concludes the description portion by a lengthy description of fibre surface measurements to which nobody, I think, referred during the course of the trial.
22. The claim as to be amended, with the features labelled for ease of reference, is as follows. I have omitted the reference numerals, which do not assist the question of construction.

An absorbent diaper having

1. an absorbent structure with a size and absorbent capacity compatible with an infant; and

2. a front waistband region a back waistband region and crotch region interconnecting said front and back waistband regions;

said diaper comprising:

3. a back sheet having a generally I-shape or modified hourglass shape;

4. a liquid permeable top sheet superposed on said back sheet;

5. tape tab fasteners applied to the back waistband region;

6. elastic members along each longitudinal edge to draw and hold the diaper against the legs of the wearer;

7. the absorbent structure having a retention portion which is positioned between said back sheet and top sheet for holding and storing a liquid;

8. the retention portion comprising a mixture of cellulosic fluff and absorbent gelling particles and densified to within about 0.08 to 0.3 g/cc; and

9. a fibrous surge management means located in liquid communication with said retention portion which serves to receive and temporarily hold discharged liquid, to transport liquid from the initial point of contact and spread it to other parts of the surge management means and to release the liquid to said retention portion;

10. said surge management means having a basis weight of at least 60 g/m²;

characterised in that

11. said surge management means has a density and resilient fabric structure which resists collapsing and preserves a void volume capacity for successive receipts of said liquid when said surge management means is wetted;

12. said surge management means providing an uptake time value of not more than about 8 seconds;

13. a temporary loading value of at least 3 gram per gram of said surge management means;

14. and a liquid residual value of not more than about one gram per gram of said surge management means;

15. said surge management means is constructed and arranged to provide said uptake time value, said temporary loading value and said liquid residual value over at least at least three uptake and desorption cycles when each cycle is conducted with 100 ml of synthetic urine using the penetration rate desorption (PRD) test described on pages 12 and 13 [sc. of the specification].

23. Features 2 to 8 of this claim reflect the common general knowledge in the art. All diapers for infants have these features. The numerical limits of feature 8 encompass all practicable retention portions. A number of difficult points of construction arise and it is convenient to construe the amended claim before considering the allowability of the amendments. The first question and most important is how to identify the surge management means in a multi-layer diaper.

The Common General Knowledge

24. I have already outlined the common general knowledge above, but it is now necessary to consider the subject in more detail. In Beloit v. Valmet [1997] RPC 489 at 494 the Court of Appeal said this:-

"It has never been easy to differentiate between common general knowledge and that which is known by some. It has become particularly difficult with the modern ability to circulate and retrieve information. Employees of some companies, with the use of libraries and patent departments, will become aware of information soon after it is published in a whole variety of documents; whereas others, without such advantages, may never do so until that information is accepted generally and put into practice. The notional skilled addressee is the ordinary man who may not have the advantages that some employees of large companies may have."

The patent specification is addressed to such a man and must contain sufficient details for him to understand and apply the invention. It will only lack an inventive step if it is obvious to such a man.

It follows that evidence that a fact is known or even well known to a witness does not establish that that fact forms part of the common general knowledge. Neither does it follow that it will form part of the common general knowledge if it is recorded in a document. As stated by The Court of Appeal in General Tire and Rubber Co v. Firestone Tire and Rubber Co Limited [1972] RPC 457 at 482 line 33

"The two classes of documents which call for consideration in relation to common general knowledge in the instant case were individual patent specifications and "widely read publications". As to the former it is clear that individual patent specification and their contents do not normally form part of the relevant common general knowledge, though there may be specifications which are so well known amongst those versed in the art that upon evidence of that state of affairs they form part of such knowledge, and also they may occasionally be particular industries (such as that of colour photography) in which the evidence may show that all the specifications form part of the relevant knowledge'."

25. The principal question was whether multiple layer structures (in which the layers were not merely wrapping for the other layers) were well known to the notional addressee at the priority date. To answer this question, one must return to the MTS report. After the passage which I have quoted above, a list of particular samples displaying interesting features including multiple layers is set out. Dr Creagan accepted in cross-examination that the layers used in these nappies might have more than one function. For example, a layer provided for mechanical strength in manufacture (a carrier layer) might also serve to prevent migration of SAM through the diaper. The 'diapers of interest' in the MTS Report were discussed with the witnesses. Thus, the multiple layer structure from P&G in Japan includes a layer of "subfacing 20gms per sq. metre spun bond thermally embossed polypropylene". This layer was accepted by Dr Creagan as being a "rewet" layer whose function is to prevent the sensation of wetness from penetrating the top surface of the diaper once used. The idea is that the rewet layer should be hydrophobic, and so not retain moisture. At the same time, it must not be impermeable to urine. The nappies which were considered were products of the market leaders in the United States, Japan and Europe. They have used not only the rewet layer, but nappies containing more than one absorbent layer: the layer closer to the skin containing no SAM. Dr Creagan accepted that the reason for the exclusion of SAM from the upper layer was a recognition of the problems of the super-absorbent material to which I have already referred, that is slow uptake and a tendency to block. He accepted also that nappies with multiple layers of this description were plainly designed to deal with multiple insults. Dr Creagan accepted that the purpose of the second fluff layer would be to take up fluids sufficiently quickly to avoid leakage and provide time for some of that material to be absorbed from the upper layer by the lower, SAM-containing layer.
26. In my judgment the skilled addressee of the specification would at the priority date have the knowledge of the function or functions of the layers which Dr Creagan displayed. He or she would know that the use of multiple layers was necessary if particular results, and in particular the avoidance of rewet, were to be avoided.
27. The first question which arises as a matter of construction is how the "surge management means" called for by the claim is to be identified. The question arises because the part of the allegedly infringing nappy identified by Kimberly-Clark as the surge management means has two components: a cross-linked curled cellulose attached to a low basis weight polyester non-woven material. P&G say that the low basis weight non-woven material should be disregarded, and, if it is, the cross-linked curled cellulose layer does not have the features called for by the claim. Thus, when they perform the PRD test on the "Depend" prior art product, P&G separated the cellulosic material from this polyester layer. The contention advanced by P&G is that as a matter of construction the surge management means is a single homogenous layer, and that layers having other primary functions are to be disregarded. Of course, this argument operates as a squeeze, since if the claim encompasses a complex layer, and if in the prior art it is possible to identify combinations of layers together forming a "surge management means" then the patent may be invalid. Dr Creagan expressed the view that there was no reason in fact why the surge management means should not contain more than one fabric, the PRD test in the specification providing a way of testing the individual fabrics and the combination away from other components. The teaching of this specification is to relate the results of the PRD test to the mixed properties of the various fibres which go to make the surge management layer. If this teaching is to be a general one, then it seems to me, at least at first sight, that there is force in the contention that the surge management means is a single identifiable layer, rather than a combination of layers each present to fulfil other functions but together would function in fact as a surge management layer within the claim. There is, as far as I can see in the specification, no suggestion that the surge management means may comprise more than one layer. The teaching of p. 12 of the specification in relation to the PRD test might be considered to be misleading if the surge management means may comprise more than one layer, at least if both layers affect the qualities of the composite. The problem is an acute one since many of the lighter absorbent materials will be manufactured on carrier materials which will be used to increase their mechanical strength. If the carrier layer substantially affects the properties of the absorbing material, then there is no teaching in the specification as to how to interpret the results of the PRD test so as to affect the properties both of the carrier and of the absorbent material.
28. The patentees Kimberly-Clark say that this analysis is far too refined. They point to the fact that the specification contemplates materials which are coforms (that is, materials containing more than one fibre in uniform admixture) and that all that is needed is to identify one component between the cover sheet and the retention portion, the component being made of either a single material, a blend of different materials or a composite. They say that the blend or composite must have portions so interconnected "that they can readily be recognised as being equivalent to a single type of material".
29. It seems to me that the straightforward meaning of the words of the claim is that it should be possible to lift out of the alleged infringement one thing which can be subjected to the PRD test. While it is true that a two layer composite bonded together can both be lifted out of the structure and subjected to the PRD test, there is no teaching in this specification as to how to apply the results of the PRD test to this material so either as to make use of the invention or so as to avoid infringement. The whole teaching of the PRD test is that it is to be applied to a "fabric". Nonetheless, in my judgment, the claimant's construction is to be preferred. There is no requirement that the specification be sufficient to produce the alleged infringement, but merely that the manufacturer of the alleged infringement be in a position properly to know whether or not the identifiable layer or means satisfies the requirements of the claim. Accordingly, in my judgment the terms 'surge management means' encompasses structures having more than one component provided that the component taken together satisfy the PRD test.

The PRD Test — Insufficiency

30. The specification must give proper directions to enable the notional addressee to perform this test, which is unique to this specification and prescribes the boundaries of the claim. A failure properly to describe the test so that there is ambiguity which cannot be resolved by reference to the common general knowledge is, in my judgment, fatal to the specification.
31. There are two parts of the test. The first is the soaking test. For this part of the test, the simple apparatus used is comprehensively described in the specification. The test involves three measurements, the first two of which are taken with this simple apparatus: the penetration times and the saturated sample weight. All the problems arise with the second half of the test which is the "desorption" test. I have quoted the relevant passage above. The problem arises in the testing of the desorption pad itself. The desorption pad, which is a pad of absorbent material, is intended to provide a standardised representation of an absorbent part of a diaper, so as to obtain some figure for the ability of the surge management material to lose urine into an absorber. There is no doubt that the passage relating to the properties of the pad is badly drafted. Two preliminary observations should be made. First, the purpose of the test is to fix the properties of the standard pad to be used in the desorption test. Second, the criterion for the pad is that it should retain "at least 10 grams" of synthetic urine per gram and therefore is a test which sets a lower limit.
32. When they came to test their desorption pads for use in the PRD test, P&G used an apparatus in which they placed the desorption pad above a box from which air was evacuated until the pressure in the box was about 0.5psi less than atmospheric pressure. This pressure difference resulted in a substantial air flow through the pad, which was maintained as the specification indicates for 5 minutes. Kimberly-Clark, on the other hand, placed an impermeable layer over the top of the pad under test with the result that the pad was subjected to a static pressure but there was no air flow. In effect, the Kimberly-Clark version of the test used the vacuum to apply a pressure of the same kind as would be applied with a weight. I repeat the very short passage describing this part of the test:

"The desorption pad should be constructed and arranged such that after an immersed saturation with synthetic urine under free-swell conditions for 5 min, the pad retains at least 10 g of synthetic urine per gram of desorption pad after being subjected to an air pressure differential (vacuum suction) of about 3.45kPa. (about 0.5 psi) applied across the thickness of the pad for 5 min."

33. The words are apt to cover both tests. In context, which is correct? The relevant context is as follows: First, the test is an arbitrary test for the purpose of standardising the desorption pad. There is no question of it reflecting in any way actual conditions of a desorption pad in a nappy in use. The material which satisfies this test will be used dry for the successive desorption of the material under test as a surge management means in the PRD test. No guidance is therefore to be obtained from the purpose of the test. It is merely a way of finding out how strong the affinity of the desorption pad for urine is. Second, the desorption test itself uses a weight to apply a pressure of 0.25 psi over the entire sample. When a static weight is to be used, it is described. Third, the desorption material described in the specification (which contains 12% of SAM) does not satisfy the test performed in the P&G way. Fourth, the test has no parallels in the common general knowledge, and no guidance is to be obtained from other sources.
34. Linguistically, it seems to me that context tends to favour the P&G view. I say this because it seems clear that when the draftsman wished to apply a pressure by the use of a weight, he was quite capable of doing so and it is not suggested that it is impossible to carry out the equivalent of the Kimberly-Clark test merely using a weight. My immediate reaction was that the P&G view nonetheless had to be wrong. I was particularly influenced by the fact that the 12% SAM material made in accordance with the directions in the specification did not satisfy the test. However, I am satisfied after reflection that my initial view was incorrect. The Kimberly-Clark version of the test implies that the draftsman has failed to describe an essential feature of the apparatus used. There is no doubt that apparatus can be constructed using the common general knowledge to apply an air pressure differential by vacuum suction across the thickness of the pad but without use of an impermeable layer. Of course, the pressure drop will be due to flow phenomena in the material rather than by a uniform pressure applied to its top surface, but that is no reason to suppose that a useful indication of the ability of the material to absorb is not being obtained. I do not believe that if a skilled man performed the test the P&G way and his 12% SAM material failed to meet it then he would necessarily realise that he ought to use an impermeable layer over lying the material to be tested. Were he to do so, and obtain a result for the 12% SAM material which was along the lines of that indicated by the specification, I think that there is real doubt as to whether the skilled man could then be confident that he did in fact have the right test.
35. The evidence on this issue came from Dr Creagan, Mr Courtray and Dr Abbott. Interestingly, Mr Courtray, who had been responsible for testing diapers at Peaudouce, had used both techniques. To begin with, he had used the open technique in combination with a Buchner funnel. He later refined the test to use an impermeable film. This was because he could not be sure which part of the pad was under pressure. From this evidence I draw the conclusion that there is no intrinsic improbability in either method. Dr Abbott was adamant that the test could be performed without an impermeable film and that it seemed to him that the results were sensible.
36. Mr Courtray's evidence, and that of Dr Creagan, was that if the 12% material does not work, then it is the test which should be investigated. That may well be right. However, ambiguity in the description of the crucial test which cannot be resolved by reference to other descriptive matter in the specification or without leads, in my judgment, to a finding of insufficiency in this case. Article 83 of the European Patent Convention requires that the application must disclose the invention in a manner sufficiently clear and complete to be carried out by a person skilled in the art. The patent may be revoked on the grounds that the specification fails to make such a disclosure. Where the boundaries of the claim are fixed by reference to a test which is described in the body of the specification, the skilled man must be in a position to perform that test so as to satisfy himself that he is, in truth, using the invention of the specification. It has long been the law that "You must not give people mechanical problems and call them specifications" - Plimpton v Malcolmson [1876] 3 Ch D 531 by Jessel M R. A more modern and comprehensive formulation of the principle is given by the Court of Appeal in Mentor v Hollister [1993] RPC 7 in the judgment of Lloyd LJ. The ultimate question depends always upon the particular facts of the case. The addressee is not to be expected to perform undue experimentation: but he is expected to correct obvious mistakes in the specification. He is not to expect every necessary detail to be given to him by the specification provided that the details omitted can be supplied from his common general knowledge, and he must of course seek success. The insufficiency with which I have to deal is one in which I am satisfied on the evidence the skilled man is not in a position to know whether he is confronted with an error in the test or not. Subject only to the question of the failure of the 12% material to satisfy the test, he is left without any clues at all. But the failure to meet the test with the 12% material using the specified wood fluff both hard and soft is not conclusive. There was no evidence that the figure for SAM which would meet the requirements of the test if performed in the P&G way (about 27%) was so out of the ordinary as to indicate to the skilled man that he had made an error. Indeed, changing the figure of 12% to 27% seems to me to be precisely the sort of experimentation that he can properly be expected to perform. Absent evidence that having performed the test in the P&G way and failed on 12% material the skilled man would, without the exercise of ingenuity and from his own common general knowledge, add to the test an apparatus feature nowhere described or referred to, it seems to me inevitable that the specification is insufficient, and I must accordingly revoke the patent on that ground.
37. A subordinate but important point on insufficiency was made in relation to the numerical limits in features 10 and 13 of the claim. The point is shortly stated. On its own, basis weight is a limitation without a functional purpose. The true criterion is total holding capacity which is given by basis weight over temporary loading for a total holding capacity in grams per gram. The reason this point is being taken is that the temporary loading value of about 3 grams per gram with a basis weight of 60 g/m² which is the lowest the claim requires, gives a total loading capacity of 180 grams per sq. metre. Example 9 of the specification of which corresponds to a prior art material to which I will come, describes a material that has a basis weight of only 26 g/m² but a high gram per gram load of about 9. giving a total load of 234 g/m² or thereabouts. Put another way, to use the example 9 material with its low basis weight as a surge management mean provides a total void volume capacity within the limits required by Claim 1. This, it is suggested, indicates that the criteria of the claim are to a large extent arbitrary. I think that Dr Creagan accepted this. It cannot affect the construction of the claim. But it does show that the claim must be given a literal construction in this respect.

Infringement

38. If I am wrong on the question of the PRD test, there is still a question whether the article tested by Kimberly Clark is properly viewed as a composite surge management means. Although stuck together, P&G say that the two layers are not a composite and it is said that the non-woven spun bonded layer is an additional rewet layer having nothing to do with surge management. So far as the Pampers products are concerned, the order of materials through a section of the product is shown in the second annex to the product description. The layer closest to the user is a polypropylene non-woven material; there then follows a polyester non-woven and cross linked cellulosic material which are bonded together to the extent only that a few fibres interpenetrate. The polyester non-woven is used as a carrier for the cross linked cellulosic portion. There is no doubt that the cross-linked cellulose is hydrophilic from any point of view and highly absorbent. The polyester non-woven material is fairly hydrophilic but certainly is sufficiently hydrophobic to have some effect on rewetting. The whole structure is described in P&G's own patent, referred to at trial as Palumbo, and in particular the passage at p.11 line 6-16. Mr Thorley submitted on the basis of Dr Creagan's evidence that the polyester layer would be plainly regarded as a "curly, wavy line" in the MTS cross-sections, that is, as a subfacing or carrier layer. At the same time, Dr Creagan accepts that the cellulosic layer would of itself perform all the functions of a surge management means as defined in the specification. Accordingly, he accepted that it fulfilled the functions of receiving the insult, distributing the insult, temporarily holding the insult and releasing it. He also accepted that that is why the cellulosic material was present in the diaper. On the basis of this evidence, Mr Thorley submits that there is no composite material here at all but two materials, one performing the established function of a carrier and a rewet layer and the other functioning as a surge management means and that accordingly only the cellulosic layer was to be tested using the PRD test.
39. In his cross-examination of Mr Moran, Mr Watson established that because there needs to be a hydrophilic gradient from the top of the nappy closest to the user to the absorbent core, the amount of residual urine in the curly cellulose layer would affect the rewetting qualities of the diaper, which would not be dictated solely by the properties of the polyester layer. However, Mr Moran was unwilling to state whether the effect would be substantial or not, since he had no tests upon which he could base his views. I have come to the conclusion that the purpose of the two layers is distinct as is their effect. The polyester spun bond layer acts both as a carrier and as a rewet layer. The cellulosic layer underlying the spun bond layer acts as a surge management means being less hydrophilic than the principal absorbent layer. At the same time, I do not believe that they can be sensibly reviewed as a composite layer having a single function. If the carrier were a pure carrier having no substantial affect upon the properties of the layer the position would be different. However, I have come to the view that notwithstanding the fact that the claim is not limited to homogeneous layers, it is nonetheless incapable of leading on to a construction whose two components have distinct functional effects. For this reason also the claim is not infringed.

Obviousness

40. The allegation of lack of novelty of the unamended claim is not pursued in the light of the concession that the claim was invalid.
41. Before turning to the allegation of obviousness, I should say something about its relationship to the insufficiency which I have identified. It is often said that a specification cannot both be obvious and insufficient. This is not necessarily the case. Here, the overall inventive concept is said to be obvious, and the particular means used to delimit the boundaries of the claim is insufficiently described. But if I come to the conclusion that whatever the limits of the PRD test, there were at the date materials obvious to make which fall within it, then the claim is bad for obviousness.
42. Three starting points are proposed for the allegation of obviousness. These are the specification called Meyer, a prior use of an incontinence aid called 'Depend'. Finally, the availability of the material of example 9 of the specification as a layer in a nappy is said also to make the invention obvious. In this case, a suitable approach to the question is to adopt the four stage analysis set out by the Court of Appeal in the Windsurfing case [1985] RPC 59. The inventive concept of the patent in suit is the provision of a structure in a multilayer nappy next to the top layer which must be "in liquid communication" with the storage core, must have a basis weight of at least 60g/m², and must have a density and resilient fabric structure resisting collapse and preserving void volume capacity for successive receipts of liquid when it is wetted. The significance of the PRD test is that a structure satisfying the PRD test will have these desirable qualities. Of course, the discussion of the total loading capacity of the surge management means above shows that not all structures having the desirable qualities will necessarily fall within the claims. To that extent, the PRD test is arbitrary and moreover forms no part of the common general knowledge. On the face of it, it might be thought difficult to show that anything falling within the claim was obvious absent proof that first of all such and such a layer was obvious to incorporate and secondly that it did in fact satisfy the PRD test.

Meyer

43. Meyer discloses (see for example Figure 2) a diaper construction in which a "liquid permeable transport layer" (18 in Figure 2) is interposed between the top sheet 14 and the absorbent body 16. Nothing turns upon the nature of the top sheet 14 or the absorbent body 16. In the structure of Figure 4, a further layer 30 is interposed between the liquid permeable transport layer 18 and the absorbent body 16 so as to provide a "distinctive wicking layer" which helps to distribute liquid rapidly into the absorbent body. The transport layer is said to be a non-woven fibrous web composed of a substantially hydrophobic material such as polypropylene, polyethylene, polyester or the like, and may also be composed of a blend of such materials. It is said to have a substantially uniform density and to have a pore size gradient through its thickness if desired. In column 9 the function of the transport layer is described as follows:

"Once the flow of liquid has been initiated into transport layer 18, it is desirable to rapidly conduct liquid through top sheet 14 and minimise any pooling of liquid against the wearer's skin. Ordinarily, absorbent body 16 by itself does not provide sufficient surge capacity. The relatively small pore sizes in capillaries within absorbent body 16 can strongly attract and hold a liquid, but do not collect and draw in the liquid at a sufficiently rapid rate. As a result, an excessive amount of time may be required to gather the liquid through the topsheet and draw it into the absorbent body. During this time, liquid can excessively hydrate the wearer's skin. ........ To retain the surge capacity and to better allow the spread and distribution of liquid laterally across the general plane of transport layer 18, the pore size within the transport layer should be substantially maintained even when the transport layer is wetted. Accordingly, a particular aspect of the invention includes a transport layer in which the effective average pore size of the transport layer does not excessively collapse when the transport layer material is wetted with aqueous liquids. Thusly configured, the transport layer can better accommodate repeated insults of discharged liquid, and can more rapidly collect and contain large and sudden surges of the liquid. The liquid can be more effectively held in a region located on the side of top sheet 14 which is opposite from the wearer's skin. In addition, the transport layer can allow rapid spread of the liquid sideways along its natural length and width dimensions to expose a larger surface area of absorbent body 16 to the liquid thereby increasing the potential rate of absorption into the absorbent body."

44. The inventive concept seems to be little different from that of the patent in suit. The idea of providing a layer which receives the discharged liquid, transports it to the main liquid storage and spreads it out are all present, as is the need for a resilient structure which resists collapse. The question therefore is whether the materials exemplified will have the qualities called for by the claim and in particular whether they will satisfy the PRD test. Indeed, the specification of the patent in suit expressly points out that a capillary force differential created at the interface between the surge management portion and the retention portion can improve the containment characteristics and this is the function of the different pore sizes referred to by Meyer. Furthermore, the surge management portion of the structure according to the patent in suit can contain both wettable (hydrophilic) and non-wettable (hydrophobic) materials. Meyer discloses one material suitable for a transport layer which has a basis weight of about 36 g/m² at column 9 lines 58 to 65. Another transport layer referred to but not exemplified has a basis weight up to 2 ounces per sq yard which is about 67 g/m².
45. Accordingly, the teaching of Meyer is to take a second layer which is to be capable of wicking the urine from the point of delivery over a wider area of the principal absorbent core. It teaches also that the transport layer must be resilient so as to accommodate repeated deliveries of urine, and that it must be less hydrophilic than the core so that the greater part of the urine is transferred to the core as the core can accommodate it. Mr Thorley submits, and I agree, that it is difficult to see any light between this teaching and the general teaching of the patent in suit subject to the question of the PRD test. Dr Creagan's evidence was that merely to increase basis weight in Meyer would not, on the assumption that polyester was being used, result in a material which would meet the PRD test. This evidence was not successfully challenged, and Mr Moran says that it is not possible to know in advance how the higher basis weight Meyer materials would behave in a PRD test.
46. The PRD test thus becomes crucial. It provides the inventive step over Meyer. No reason is suggested why the basis weight limitation of 60 g/m² has any effect upon the performance of the invention, nor could it having regard to the factors to which I have referred above. Basis weight is of no significance until coupled with the temporary loading value.
47. The teaching of the patent in suit is essentially two-fold. First it describes the need for a resilient portion of the nappy capable of acting repeatedly to accept and distribute surges of urine and secondly it provides, in the PRD test, a method of conveniently testing materials which if they pass the PRD test will have desirable characteristics. It seems to me that the PRD test is in truth irrelevant to the inventive concept of the patent in suit. When the inventive concept is communicated to the skilled man, he is pointed in the right direction to arrive at a better nappy. Both Meyer and the patent in suit make this communication. The presence of the PRD test in claim 1 does not, it seems to me, add anything of inventive significance. In my judgment once the skilled man has taken the teaching of Meyer on board, then the patent in suit should not be capable of preventing him from using that teaching. It cannot be suggested that there is no chance of that being the case. In putting the teaching of Meyer into effect, it would not require an inventive step to fall within the scope of the claims of the patent in suit and it follows the latter are invalid.
48. The claims alleged to be independently valid are claims 2 (if claim 1 is invalid over Meyer), claims 3, 4, 5, 6, 20, 23 and 24. Claim 2 adds a basis weight range for the surge management means of 90 - 3,000 g per sq metre. Meyer in fact contemplates rather high basis weights if the ranges for density and thickness for the transport layer are taken independently. I am satisfied in any event that these ranges are extravagant. Three kilograms per sq metre is a high basis weight for a material intended to be used in a nappy. Reasonable weights seem to me to be intrinsically obvious in the light of Meyer. Claims 3, 4, 5 and 6 are claims to different limits in the PRD test. The precise value of the limits cannot affect the analysis which I have given of the test, which I consider to be devoid of inventive significance. Accordingly, these claims are not independently valid. Claim 20 merely adds an even higher lower limit for the basis weight of the surge management means which is again obvious for the reason which I have given. Claim 23 specifies that the retention portion include a recess area which at least partially surrounds the surge management means. It is not entirely clear what this means, and the words may be intended to cover a structure in which the surge management means is let into the retention portion. This is trivial. It is plainly obvious as a possible construction. Finally, Claim 24 calls for the surge management means to be composed of a mixture of fibres. This is specifically taught in Meyer. It follows that none of the claims alleged to be independently valid have any independent validity.

Depend

49. Depend is an adult incontinence garment which if Procter & Gamble are right on construction, as I have held that they are, has a layer of material (referred to as "coform") which in the absence of a spun bond carrier layer falls within the PRD test. If the spun bond carrier layer is included, then Depend is outside the uptake time requirement of claim 1.
50. Prior to amendment there is no doubt in my judgment that Depend anticipated the claim. The effect of the limitations to devices for use with children excludes Depend, and the question becomes one of deciding whether it was obvious to use the layer in a child's nappy. I am quite satisfied that it was. The same general teams are responsible for the development of advances in both child diapers and adult incontinence garments, and there was no convincing evidence that the common general knowledge of the designers differs. Indeed, there is some indication that the many patents in this field cover the two indifferently. Indeed, the only real objection to the use of the Depend coform layer is its cost and this is a purely commercial consideration without technical significance. It is irrelevant to the obviousness of the step. Claim 1 is invalid in the light of this product.

The Example 9 Material

51. In the end, the case made on the example 9 material added little or nothing to the case on Meyer, which contains the crucial teaching which is absent from the mere offer for sale of the example 9 material. On its own, I do not believe that the availability of the example 9 material would have taken the skilled man anywhere, and this attack of obviousness fails.

Amendment

52. The patent in suit was applied for some ten years ago. It is under opposition in the European Patent Office, and the opposition proceedings have not concluded. The patent was granted on 31 July 1996, and opposition must, therefore, have started before 30 April 1997. Accordingly the patentees apply to amend their European Patent (UK) in the manner in which it will be amended by the European Patent Office if the amended claim is valid. The Court of Appeal has held, in a judgment now reported at [2000] RPC 422, that the well established jurisdiction to refuse amendment on discretionary grounds continues. The patentees accordingly called evidence from Mr Paul Yee, a Patent Attorney employed in the legal department of Kimberly-Clark Corporation. He has the task of supervising the opposition proceedings, and was responsible for the foreign filings, including the application in the EPO. He was not responsible for drafting the original US application from which the European application claims priority. The amendments with which I am concerned are substantially identical to those offered in the European Patent Office. The opposition division has considered the proposed amendments and has held them to be formally allowable. I agree. The objections to allowability (as opposed to discretionary matters) which are raised by P&G are raised in respect of three passages in the claim. I shall take them in turn.
53. The addition of the words "having an absorbent structure with a size and absorbent capacity compatible with an infant" are objected to on the grounds that they are hopelessly ambiguous. As a matter of commerce, nobody seems to have any difficulty in identifying a child's diaper, and if nobody in the art seems to have any difficulty I do not see why the Court should be astute to say that these words are ambiguous. There is nothing in this objection.
54. The words "serves to receive and temporarily hold discharged liquid, to transport liquid from the initial point of contact and spread it to other parts of the surge management means" are objected to on the grounds that they add matter if they serve to exclude things which pass the PRD test. In their context in the claim, it seems to me that the words are disclaimers if they have any effect, and have support in the specification in the passages to which I have already referred. Again, I consider this amendment in principle allowable though probably unnecessary.
55. The words "surge management means has a density and resilient fabric structure which resists collapsing and preserves void volume for successive receipts of said liquid when said surge management means is wetted" are said to add matter unless the word resilient is explanatory of the PRD test. I do not accept this. The description of the surge management means of the patent in suit at p.9 line 45 ff is plainly directed to a resilient fabric. I consider that the objection is misconceived.
56. This brings me to the question of discretion. The objection is one of covetousness. It is contended that the patentees have at all material times known that all three parameters of the PRD test are necessary for the purpose of defining the invention and that the temporary loading capacity should not have been added by amendment but present in the claim from the outset. It is also said that they knew that an incontinence guard called "Serenity" manufactured by Johnson & Johnson only failed to fall within the claim because it did not have the required temporary loading value. Finally, it is said that they knew that the "Depend" incontinence garment, to which I have already referred, had an acquisition layer which satisfied the claim before amendment, which is admitted.
57. Mr Thorley contended that it followed from Donaldson's Application [1986] RPC 1 that the omission of a feature going to the essence of the invention from the claim constitutes covetousness. In that case, Falconer J considered the decision of the Patent's Appeal Tribunal (Graham and Whitford JJ) ICI (Whyte's) Patent [1978] RPC 11. In the latter case, Graham and Whitford JJ said this:

"It is also vital to appreciate that a charge of covetousness, if it is to be successful, must involve proof to the satisfaction of the Court that the patentee has knowingly and deliberately obtained claims of unjustified width. Such was evidently the view taken by Simonds J in Howlett's case and he obviously considered that the patentees there were asserting a right to something to which they knew they were not legally entitled. If such is proved to the satisfaction of the Court, it is no doubt correct as a matter of discretion to refuse amendments limiting the claim on the basis that the Court will not assist a wrongdoer."

Falconer J said this:

"In my judgment, the Superintending Examiner was right in regarding the clear statement of principle in the first sentence of the quoted passage as the test of what is required to establish a case of covetous claiming. It seems to me that quite clearly what follows in the second sentence of the quoted passage is merely the Tribunal's explanation of how the decision in Howlett's case fell within the general principle enunciated in the previous sentence and was not intended to restrict the ambit of that general principle by limiting its application to cases where the patentee knew he was not legally entitled to the claim he sought and maintained. I do not, therefore, accept the submission of Mr Thorley.

Nor do I accept the submission of Mr Carr for the respondents that the ICI case makes it clear that to be a covetous claim the patentee must have known that the claim he sought and maintained was invalid. Of course such a case would fall within the general principle stated in the first sentence of the quoted passage, but the ambit of the principle is not limited to such cases."

Falconer J went on to approve a finding by the Hearing Officer that the claim before amendment omitted what the patentees knew to be their inventive feature, and held that the claim prior to amendment had been covetous.

58. In my judgment, a claim of covetousness cannot begin to be made out unless it is established that the draftsman of the specification sought to obtain a claim of a breadth which was unjustified on the material available to him. That material will include the description of the invention, and such information as he has concerning the prior art. I would however caution against an approach which substitutes for a draftsman's bona fide assessment of the breadth of protection which he can obtain in the light of the prior art which has been located by him or on his behalf an assessment made ex post facto in the knowledge of material of which the draftsman was unaware or the significance of which he failed, in good faith, to appreciate. I do not believe that it is a correct exercise of this discretion to refuse amendment in the absence of conduct which can fairly be described as blameworthy.
59. It is settled law that the patentee has a duty to place the whole story before the Court (see for example Chevron's Application [1970] RPC 580). I think that the duty to make full and frank disclosure referred to in Chevron has now to be seen in the light of what is said in the Court of Appeal in the instant case. Before the patentee is required to undertake a wide ranging exercise in disclosure there must be adequate grounds for supposing that discretionary grounds for refusing the amendment truly exist. In the present case, Mr Yee was criticised as a poor witness, a criticism which I do not accept and the patentees were criticised for not having produced evidence either from the inventors or from the patent attorney primarily responsible, Mr Chiatalas. Mr Yee came to the case when the priority document had been drafted. He had items of prior art which he had found in the file or had been brought to his attention by the inventors. He was cross-examined about the work which he had done in early 1989. So far as Serenity is concerned he appears to have been aware of it since the inventors had defined their invention by reference to it. He felt that the omission of the temporary loading value from claim 1 was justified on the prior art of which he was aware and the discussions which he had had with the inventors of which, unsurprisingly, he had little specific recollection. He said that he relied upon the discussions which he had with the inventors to satisfy himself that he had sufficiently distinguished the Serenity item.
60. Mr Thorley criticises the patentee because their attorney considered only bare novelty, but not inventiveness, and so broadened the invention claimed beyond that disclosed by the inventors Shershin, Matthews and Latimer. In my judgment this is the function of the patent agent or attorney. It is not a matter of criticism that the broadest claim formulated has bare novelty if the patent agent considers that it can be successfully prosecuted through the patent office. That is his job. What is blameworthy is to formulate a claim which covers that which is old, to the knowledge of the applicant.
61. Mr Yee was criticised for describing the inventors' view that all three aspects of the PRD test, and not merely the two which found their way into the claim, as being the "best mode", rather than the only mode, of carrying the invention into effect. I do not accept this. Had there been evidence from a competent expert in US patent drafting to suggest that Mr Yee's approach (or Mr Chiatalas's evident approach) was wrong from the US perspective, then perhaps this objection would have had more substance. But I am very reluctant to criticise him when I have no knowledge of how a reasonable patent attorney should draft a specification as a matter of US practice, and I decline to accept that it is necessarily correct that standards applicable to the drafting of a domestic British application should be applied without examination to an application which started life in the United States and was prosecuted to grant in the European Patent Office by a German firm of patent attorneys without any reference to British practice at all.
62. In the result, I do not consider that there are any grounds upon which the amendment in the present case should be refused. But the patent as proposed to be amended is invalid, and must be revoked.