Case Comment

Auchincloss v. Agricultural & Veterinary Supplies Ltd.

citation(s): [1997] R.P.C. 662 (Patents Court per Peter Prescott, Q.C.)

copyright 1997 Donald M. Cameron, Aird & Berlis




The Decision

At p. 662-663:

II. Construction

The law

The Patents Act 1977 in large part implements the European Patent Convention. Article 69 (cf. section 125 of the Act) says:

The extent of the protection conferred by a European patent … shall be determined by the terms of the claims. Nevertheless, the description and drawings shall be used to interpret the claims.

The Protocol on the Interpretation of Article 69 says:

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

In telling us that one must adopt a position between these extremes the Protocol is generally understood to be rejecting, and maybe even caricaturing, on the one hand, the approach alleged to have been adopted by the English courts in former times, typically before the War, and on the other hand, the approach alleged to have been adopted in the past by the courts of Germany. If it stopped there, perhaps the Protocol would be affording somewhat uncertain guidance, but it does not stop there. The concluding words require two conditions, both of which are mandatory: a fair protection for the patentee, and a reasonable degree of certainty for third parties.

Although there has been some difference of opinion at Court of Appeal level, a long line of authorities which are binding on me holds that the appropriate standard is that described by Lord Diplock in the Catnic case. I need not cite all of these not least because both sides simply assumed that Catnic was applicable.

At p. 664-666:

In quoting this passage I have twice emphasised the word descriptive. It is a descriptive word or phrase to which the concept of an immaterial variant applies. In the cited case the ‘descriptive’ phrase was "extending vertically". If, instead, the claim had said "extending at an angle between 87.0° and 93.0°", this would not have been a descriptive phrase, but a specification of a precise range. It would be a unilateral statement in words of the patentee’s own choosing informing the reader what he claimed to be an essential feature of his invention. If a product fell outside that range it would not be a question of a ‘variant’ at all, minor or otherwise. It would be a failure to adopt an essential feature. Even if an angle falling somewhat outside that range would work just as well, and his were obvious to all concerned, to hold non-infringement would not be to deny ‘a fair protection for the patentee’ in terms of the Protocol to the Convention; for the range he chose to specify was one which he himself must have considered to be fair at the relevant date. On the contrary, to hold otherwise would be to deny ‘a reasonable degree of certainty for third parties’. In so saying I believe that I am supported by Hoffmann J’s exposition of the third Catnic question, see below. This is relevant, particularly to the counterclaim.

In Improver Corp v. Remington Consumer Products Ltd. [1990] F.S.R. 181, Hoffman J, in a passage frequently followed and applied, held that the Lord Diplock standard was the one appropriate to the Convention and Protocol. He paraphrased and explained the Catnic test as one involving three questions.

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

    1. Would this (i.e. that the variant has no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art. If no, the variant is outside the claim. If yes –
    2. Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention. If yes, the variant is outside the claim.

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

Thus in Catnic itself … the conclusion was that "extending vertically" meant "extending with the range of angles which give substantially the maximum load-bearing capacity and of which 90° is the perfect example.

In the end, therefore, the question is always whether the alleged infringement is covered by the language of the claim."

Applying that reasoning to the facts of the case before him, Hoffman J. held that a claim which required the presence of a "helical spring" was not satisfied by a grooved, rubber rod which behaved in the same way. The third question was to be answered in the affirmative. This was because the problems inherent in rubber rods had not been explored, but

"On the other hand, drafting the claim in wide generic terms to cover alternatives like the rubber rod might be unacceptable to the patent office. I do not think that the hypothetical skilled man is also assumed to be skilled in patent law and he would in my judgment be entitled to think that the patentee had good reasons for limiting himself, as he obviously appeared to have done, to a helical coil. To derive a different meaning solely from the equivalents clause would in my view by denying third parties that reasonable degree of certainty to which they are entitled under the Protocol." [1990] F.S.R. 181 at 197.

In Sociéte Technique de Pulverisation Step v. Emson Europe Ltd. [1993] R.P.C. 513, 522 16-20, C.A., Hoffmann L.J. said:

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

‘Integer’ is a well known term of art. It means a feature called for by a claim. It might be a physical component; or it might be some other definite limitation, e.g. a requirement that a value fall within a specified numerical range.

In Optical Coating Laboratory Inc. v. Pilkington P.E. Ltd. [1995] R.P.C. 145, 158, C.A., Balcombe L.J., delivering the judgment of the court, posed the three Improver questions and continued:

The "variant" in the present case is that there is no layer of absorbent material, but that it is the substrate itself which is absorbing… It is in answering this third [Improver] question that the matter of obviousness becomes relevant. If one asks the question: why should the patentee have intended that the variant of placing a stack of reflecting layers on an absorbing substrate should not be within the ambit of the invention claimed? Then the answer may well be; because such a solution to the problem posed was then obvious to a person skilled in the art. Or as Lord Diplock said in Catnic (supra) at page 244:

No plausible reason has been advanced why any rational patentee should want to place so narrow a limitation on his invention.

A plausible reason in the present case is that to make the invention as wide as is now claimed would have been to risk rendering the whole patent void for obviousness."

In the Beloit case, already cited, Jacob J. discussing ‘equivalents’ said (at 720 44-48);

"In all this it must be remembered that it is the patentee which has set out the limits of his monopoly. Moreover, those reading his claim are entitled to see that it has a scope that goes thus far and no further and to design around the patent. There is no such thing as the tort of non-infringement."

Finally, and on a somewhat different aspect in Willemijn Houdstermaatschappij BV v. Madge Networks Ltd. [1992] R.P.C. 386, 399. C.A., Stuart-Smith L.J., delivering the judgment of the court, said:

"Moreover in our judgment there is force in the submission made by [counsel for the defendant] that the [patentee’s approach involved an attempt to distil the essence or principle of the patent in suit and that it seeks to do so in the light of the alleged infringement. (…) In Codex Corporation v. Racal-Milgo Limited [1983] R.P.C. 369 at 381 line 49, May L.J. giving the judgment of the court said, after referring to the passage in Lord Diplock’s speech in the Catnic case which we have cited earlier in this judgment:"

"… there is no suggestion in Lord Diplock’s speech that one should look only to the essence or principle of a patent in suit and hold there to have been infringement merely because that essence or principle has been made use of by the alleged infringer. There may have been, or there may not. The question to be asked is one of construction, but of purposive or realistic construction through the eyes and with learning of a person skilled in the art, rather than with the meticulous verbal analysis of the lawyer alone."

I mention this last aspect because the plaintiffs were at pains to contend the "thrust" of their patient was the use of a low amount of sodium chloride. This they sought to turn to account, as it were, the defendants’ contention that the allegedly infringing product had little salt if it had any. This will not do. While it is true that the invention sets out to solve a problem by the use of a much smaller amount of sodium chloride than was previously present in products working on broadly similar lines, it uses some. The "thrust" of the patent insofar as it has one for present purposes, is that there must be as much salt as its claims, duly construed, require.

At p. 688-690:

It is, as I have said, common ground that the amount of sulphamic acid is outside the upper limit of claim 1, at least formally. (There are other ways of expressing the point, as I have shown; but that is the simplest.) It is also common ground that the departure does not affect the way the invention works and that this would be obvious to the skilled reader. Thus if the departure counts as a ‘variant’ the first two Catnic/Remover questions are to be answered in favour of the plaintiffs.

Counsel sought to maximise or minimise the departure, depending on whose side they were on. The defendants said it is amply outside. The plaintiffs said it is not outside by much. (This depends on the ‘parts by weight’ argument and on what might be called ‘presentational’ factors.)

I believe this dispute is neither here nor there. In making these submissions the parties were really inviting me to apply a subjective standard according to no recognised canon or, if you will, to exercise a value judgment as between incommensurables. Thus if it is outside the claim, properly construed, it is no answer for the plaintiffs to say the departure is "only a little one". See what Jacob J. had to say about the alleged tort of non-infringement in the Beloit case, above. If the patentee would be considered to have intended to cover ‘variants’ which do not affect the way the invention works, even a substantial one (as judged by this subjective standard) would make no difference. The variant in the Catnic case itself, if judged subjectively, which is what the Court of Appeal was really doing, was quite glaring, as I have attempted to explain when discussing that case, above.

Further, it would be impossible to draw the line so as to achieve a fair protection for the patentee and a reasonable degree of certainty for third parties as is required by the Protocol to the Convention. The public are entitled to know to a reasonable degree of certainty what are the limits of the monopoly, and to design around it. They are also entitled to know this for the purposes of deciding whether the claim is invalid and may be ignored, or challenged in legal proceedings, not least because the cost of challenging validity can be enormous. This is a point which tends to be overlooked. On the other hand, if the variant obviously does not affect the way invention works, and there is no other ground for saying the patentee must have intended to exclude variants, how could the presence of a subjectively large departure make it fair to the patentee to hold non-infringement?

This case, then, raises the question of how to construe claims which specify ranges, that is, upper and lower limits expressed in numerical terms. Mr. Howe contended that these do not raise any Catnic questions at all. Alternatively he said that the patentee would be taken to have limited his monopoly for reasons of his own, in other words, that the third Catnic/Improver question should be answered favourably to the defendant. He prayed in aid his point about this being a "recipe" claim.

In my judgment the departure from the defined numerical range is not a ‘variant’ at all in the Catnic sense. As I have pointed out in the section headed ‘Construction: the law’, this presupposes a descriptive word or phrase, like "vertically". The aim of the Catnic line of cases is to ascertain the purpose of the patentee, but objectively, that is, through the eyes of the skilled reader of the document. Where the patentee has expressed himself in terms of a descriptive word or phrase there may be room for supposing that he was using language figuratively, and did not intend to restrict himself to the purely literal meaning. But where the patentee has defined an integer of his claim in terms of a range with specified numerical limits at each end, his purpose must be taken to have been to claim thus far and no further. His reason for doing so may not be apparent, but it may exist all the same, for instance it may lie "buried in the prior art". Further, in this case I believe that there are evident reasons of convenience and certainty which would have led him to claim in this way, as I have already observed.

The claim here says "3 to 8 parts by weight of sulphamic acid". I can see that there could be cases where it could be said that the numerals 3 and 8 are merely values rounded to the nearest integer. (So to speak, the most perfect member of their class, to use Hoffmann J.’s phrase.) This may depend on how people in the art use language. For example, in common parlance when it is said that a competition is open to those aged from 18 to 35 it is understood that a person may enter before his 36th birthday: here, 35 means "less than 36.0". In science and engineering the use of numbers may indicate the degree of precision intended; there may be rounding; thus a chemist who says "3 to 8" may not be intending to say 3.0 to 8.0". However that may be, it makes no difference in this case. I do not have evidence of how those skilled in this art use this language, and the defendant’s revised composition is outside those numerical limits even allowing for the possibility.

In case I am wrong about there being no ‘variant’ here, I must answer the third Catnic/Improver question. Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? I take it that the reference to "the language of the claim" does not mean that I must look at the claim in blinkers. I must be able to read the claim in the light of the specification as a whole, as indeed the Protocol requires me to do.

The primary meaning is, as I have said, 3 to 8 parts by weight of sulphamic acid. For the reasons I have given at various places in this judgment I hold that the skilled reader would indeed understand that the patentee intended that a strict compliance with those limits was an essential requirement of the invention. To summarise: (a) seeing that the du Pont patent is acknowledged, the invention in suit would be perceived not to comprise some new and far ranging principle, but to be more in the nature of a class of recipes where numerical limitations may be material; (b) despite this it can be seen that the limits of the claim are to some degree arbitrary but this is perfectly understandable since the patentee may have wished to achieve certainty and convenience; and (c) the patent says that there is "extensive" prior art, the skilled reader is not taken to know the details of this, and he would suppose the patentee had intended to limit himself for reasons of his own which might lie buried in the prior art.

More generally, since it is always possible that the reason may lie buried in the prior art, I believe that a claim to a range with numerical limits at each end must be taken to mean what it says.

I therefore hold that the defendants’ revised composition would not infringe the claims of the patent in suit.


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