Manual of Patent Practice

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Section 125: Extent of invention

Sections (125.01 - 125.25) last updated: April 2011.

125.01

s.130(7) is also relevant

Section 125 is intended to have, as nearly as practicable, the same effect as the corresponding provisions of the EPC, PCT and CPC.

 
Section 125(1)
For the purposes of this Act an invention for a patent for which an application has been made or for which a patent has been granted shall, unless the context otherwise requires, be taken to be that specified in a claim of the specification of the application or patent, as the case may be, as interpreted by the description and any drawings contained in that specification, and the extent of the protection conferred by a patent or application for a patent shall be determined accordingly.

125.02

This sub section sets out the meaning of an invention as that specified in a claim as interpreted by the description and any drawings, the protection conferred being determined accordingly. (The words “for a patent” in s.125(1) have apparently been inadvertently transposed and should follow the word “application” (first appearance), so then the sub­ section should read: “For the purposes of this Act an invention for which an application for a patent has been made or ….. etc”). It thus concerns the way in which the specification should be construed in this respect but does not impose any requirement with which the applicant must comply. Objection therefore should not be raised by the examiner under s.125(1) as such, although its provision may sometimes usefully be referred to when objecting on other grounds, eg under s.14(5). For example when a claim read on its own appears to be clear and to define the invention, such an objection under s.14(5) may arise if there is matter in the description which is inconsistent with the claim or in some other way casts doubt on the true scope of the invention, see 14.88.

125.03

In the light of s.125(1), the claims should not be considered in isolation. Lord Porter’s dictum under previous law in Electric and Musical Industries Ltd v Lissen Ltd 56 RPC 23 that “if the claims have a plain meaning in themselves, then advantage cannot be taken of the language used in the body of the specification to make them mean something different” is no longer applicable (see also 125.11).

125.04

In approaching the construction of the claims the specification as a whole should be read to obtain the necessary background, and in some cases the meaning of the words used in the claims may be affected or defined by what is said in the body of the specification. In Palmaz’s European Patents (UK) ([1999] RPC 47, upheld on appeal [2000] RPC 631) Pumfrey J held that words of degree such as “thin” must take their meaning from the context. Different meanings could not be attributed either to exclude acknowledged prior art or to be consistent with representations made by the patentee’s patent attorneys in a letter to a patent office. Another example is Glatt’s Application [1983] RPC 122 at page 129, where Whitford J considered that if a particular claim were looked at alone, it would not be assumed that a certain fabric was one which was in itself necessarily and inherently air­ permeable. However, against the description of the invention in question “on its true construction the claims of the specification could properly only be read as being limited to an article suitable for conditioning fabrics comprising a flexible woven or non-woven air­ permeable web”.

125.05

In Hoechst Celanese Corp v BP Chemicals [1999] FSR 319 the Court of Appeal held that there was no rebuttable presumption that words in a patent specification which could have a technical meaning did have that meaning. The court was entitled to hear evidence on the meaning but thereafter had to decide on the meaning from the context in which they were used. See also 14.111 with regard to words used in a claim which are given a special meaning by the description. Caution should be used in considering the purpose or advantage of the invention. In Union Carbide Corp. v BP Chemicals Ltd [1999] RPC 409, it was held that where a stated advantage of the invention was that certain equipment was not required, the fact that a person used that equipment did not mean that he was not using the invention as he may have decided to use it badly.

125.06

s.125(3) is also relevant

Section 125(1) should be construed in the light of the Protocol on the Interpretation s.130(7) of Article 69 of the EPC, see 125.10, and in such a way as to have, as nearly as practicable, the same effect as Article 69(1) of the EPC, see 125.09.

Biotechnological inventions

125.07

Schedule A2 to the Act was introduced by the Patents Regulations 2000 (2000 SI No 2037) as part of the implementation of Directive 98/44/EC on the legal protection of biotechnological inventions. Paragraphs 7 to 10 of the Schedule set out certain rules for the construction of claims which relate to biological material or to processes that enable biological material to be produced - see 76A.07-09.

 
Section 125(2)
It is hereby declared for the avoidance of doubt that where more than one invention is specified in any such claim, each invention may have a different priority date under section 5 above.

125.08

If a claim is construed to specify more than one invention, the priority date of each invention should be determined separately (see the chapter on s.5, particularly 5.20 to 5.25.

 
Section 125(3)
The Protocol on the Interpretation of Article 69 of the European Patent Convention (which Article contains a provision corresponding to subsection (1) above) shall, as for the time being in force, apply for the purposes of subsection (1) above as it applies for the purposes of that Article.

The Protocol on the Interpretation of Article 69 of the EPC

125.09

Article 69(1) of the EPC corresponds to s.125(1) of the Act and reads:-

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

125.10

Both Article 69 of the EPC and s.125(1) of the Act should be construed in the light of the Protocol on the Interpretation of Article 69 of the EPC, which reads:

Article 1
General principles
Article 69 should not be interpreted as meaning 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. Nor should it be taken to mean 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 patent proprietor has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties.

Article 2
Equivalents
For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims.

125.11

In Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9, Lord Hoffmann held that the Protocol was a protocol on the interpretation of Article 69 of the EPC, and not on the interpretation of claims. The first sentence does deal with the interpretation of claims and to understand it, it was necessary to know something about the rules which English courts used to apply, or impose on themselves, when construing not merely patents, but documents in general. The second sentence does not deal with the interpretation of claims. Instead, it makes it clear that one cannot go beyond the claims to what, on the basis of the specification as a whole, it appeared that “the patentee had contemplated”. The last sentence indicated that, in determining the extent of protection according to the content of the claims but avoiding literalism, the courts of the contracting states should combine “a fair protection for the patentee with a reasonable degree of certainty for third parties”.

125.12

The requirements of the Protocol to give fair protection for the patentee and a reasonable degree of certainty for third parties were considered by the Patents Court in Merck & Co Inc v Generics (UK) Ltd [2004] RPC 31. It was held that the Protocol required that the monopoly should cover all the embodiments, whether explicitly mentioned in the claims or not, which the notional skilled reader would conclude, with reasonable confidence, the inventor wanted to cover. Where it was clear that the patentee did not intend to obtain protection for particular variants, it was not open to the court to extend the monopoly to cover them. Similarly, if a notional skilled addressee could not conclude with reasonable confidence that the inventor wanted to obtain protection for a particular embodiment, it had to follow that the patent conveyed the message that the patentee might well have intended to exclude that embodiment. To give protection in such circumstances would run the risk of going against the intention of the patentee, thereby being unfair to him, and would not be giving third parties a reasonable degree of certainty as required by the Protocol. When considering the requirements in Pharmacia Corp. v Merck & Co. Inc. [2002] RPC 41, the Court of Appeal noted that factors in balancing reasonable certainty and fair protection may include the need not to stifle research and healthy competition, and the need not to construe the patent beyond the ambit intended by the patentee.

Purposive construction and the Catnic principle

125.13

The reference in the first sentence of the Protocol to “resolving an ambiguity” rejects a literal approach to the construction of patent claims, where words were given their “natural and ordinary meaning” of words, ignoring their context or background unless they were ambiguous. The old English rules for claim construction as outlined by Lord Porter in Electric and Musical Industries Ltd v Lissen Ltd 56 RPC 23 (see 125.03) therefore no longer apply. The courts did, however, begin to abandon these rules prior to the Protocol in favour of purposive construction of claims, by giving effect to what would have been understood by the notional addressee. In Catnic Components Ltd and another v Hill and Smith Ltd [1982] RPC 183, Lord Diplock stated (at page 243):- “A patent specification should be given a purposive construction rather than a purely literal one derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge”.

125.14

When applying a “purposive construction”, the question is always what the person skilled in the art would have understood the patentee to be using the language of the claim to mean as held by the House of Lords in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9. The skilled reader is taken to suppose that the patentee knew some patent law – that his claim is for the purpose of defining the monopoly and that it should be for something new, as held by the Court of Appeal in Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd [2010] RPC 8. Knowledge of that may well affect how the claim is construed. For instance, the patentee would not be expected to have claimed what he had expressly acknowledged was old. In Kirin-Amgen, Lord Hoffmann held that purposive construction does not mean that one was extending or going beyond the definition of the claims. The language chosen was usually of critical importance, with the specification being a unilateral document in the words of the patentee’s own choosing, usually chosen on skilled advice. On the other hand, it must be recognised that the patentee is trying to describe something which he regarded as new, which had not existed before and on which there might be no generally accepted definition. It was acknowledged that there will be occasions upon which it will be obvious to the skilled man that the patentee must in some respect have departed from conventional use of language or included in his description of the invention some element which he did not mean to be essential, but such occasions would not be expected to happen very often. Furthermore, obviously intentional elements cannot be disregarded from a claim. Following Kirin-Amgen, the Court of Appeal in Occlutech GMBH and anr v AGA Medical Corp. and anr [2010] EWCA Civ 702 held that cases in which the patentee can be assumed to have departed from the conventional meaning of the words of the claim are likely to be rare, and in practice the skilled person would only give them an extended meaning where the idea encompassed in the invention is difficult to define or where the language of the patent as a whole compels that conclusion. In Société Technique de Pulverisation STEP v Emson Europe Ltd [1993] RPC 513, Hoffmann LJ held that “… purposive construction does not mean that an integer in a claim 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 some reason of his own for introducing it.”

125.15

There is no binding authority or legislation in the United Kingdom which allows use of the prosecution history of a patent as an aid to claim construction (an approach sometimes referred to as file wrapper estoppel). Accordingly, in Telsonic’s Patent [2004] RPC 38, Laddie J expressed reluctance to accept that file wrapper estoppel has any part to play in construing a patent and its claims. It was held that patents and their claims are meant to be statements made by the patentee to the relevant public, and that their meaning and effect should be discernible from the face of the document. In Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9, Lord Hoffmann held that the meaning of the patent should not change according to whether or not the person skilled in the art has access to the file. Where the extent of protection claimed has been restricted during the prosecution of the application and no explanation for the restriction is provided, there is no presumption that there must have been some good reason between the patentee and the patent office.

Relationship between the Protocol and the Catnic principle

125.16

In Assidoman Multipack Ltd v The Mead Corporation [1995] RPC 321 Aldous J held that it cannot be disputed that “purposive” construction, as suggested by Lord Diplock in the Catnic case (see 125.13), fits squarely within the guidelines of this Protocol. Moreover, after reviewing the authorities of the Court of Appeal, he confirmed that the correct approach to construction under the Patents Act 1977 is “purposive” construction. This was approved in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 by Lord Hoffmann: “The Catnic principle is therefore in my opinion precisely in accordance with the Protocol. It is intended to give the patentee the full extent, but not more than the full extent, of the monopoly which a reasonable person skilled in the art, reading the claims in context, would think he was intending to claim.”

Equivalents as a guide to construction and the Protocol questions

125.17

Although article 69 prevents equivalence from extending protection outside the claims, Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 held that there is no reason why equivalence cannot be an important part of the background of facts known to the skilled man which would affect what he understood the claims to mean. Guidance of the relevance of equivalence to claim construction was offered by Lord Diplock in the Catnic case:

“A patent specification should be given a purposive construction rather than a purely literal one… The question in each case is: whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked.

The question, of course, does not arise where the variant would in fact have a material effect upon the way the invention worked. Nor does it arise unless at the date of publication of the specification it would be obvious to the informed reader that this was so. Where it is not obvious, in the light of then-existing knowledge, the reader is entitled to assume that the patentee thought at the time of the specification that he had good reason for limiting his monopoly so strictly and had intended to do so, even though subsequent work by him or others in the field of the invention might show the limitation to have been unnecessary. It is to be answered in the negative only when it would be apparent to any reader skilled in the art that a particular descriptive word or phrase used in a claim cannot have been intended by a patentee, who was also skilled in the art, to exclude minor variants which, to the knowledge of both him and the readers to whom the patent was addressed, could have no material effect upon the way in which the invention worked”.

125.18

In Improver Corporation v Remington Consumer Products Ltd [1990] FSR 181, Hoffmann J formulated Lord Diplock’s approach in Catnic into three questions which the court should ask itself. These have subsequently become known as the ‘Improver’ questions, and in Wheatley v Drillsafe Ltd [2001] RPC 7 were re-named by the Court of Appeal, the ‘Protocol questions’. These questions are:

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

(ii) Would this fact (ie that the variant has no material effect) have been obvious to the skilled person at the date of publication of the patent? If no, the variant falls outside the claim. If yes:­

(iii) 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. If no, then the variant falls within the scope of the claim.

In Improver, the judge decided that a patent to a depilatory device using a bowed, helical spring rotated by a motor to grip and remove hairs was not infringed by a device in which the spring was replaced by a bowed, cylindrical rubber rod having a number of parallel radial slits, by answering the three part question as follows - (i) the change to a rubber rod had no material effect on the way the invention worked; (ii) it would have been obvious to an expert that the rubber rod would work in the same way; but (iii) the expert would have understood from the patent that the patentee meant to confine his claim to a “helical spring”, in its primary meaning and not in a wide generic sense. The rod was not an approximation to the spring, but a different thing which could in limited circumstances work in the same way. A clause in the description of the patent which stated that “all variations which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein” was not so wide as to bring in all functional equivalents, but was merely a reminder that the claims must be interpreted in accordance with Catnic and the Protocol. The Court of Appeal in Wheatley v Drillsafe Ltd [2001] RPC 7 confirmed that the reference to the skilled person in the third question is not an invitation to re-write or re-interpret the claim in the patent in question in a manner that the patentee would have had in mind, had he only thought of the variant now developed.

125.19

In Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9, Lord Hoffmann thought a better way of putting his second Protocol question may be to consider whether the variant “solves the problem underlying the invention by means which have the same technical effect”. This avoids the ambiguity over whether the question of determining if the variant “works in the same way” involves an assumption that it works at all (see also 125.23).

125.20

In Merck & Co Inc v Generics (UK) Ltd [2004] RPC 31, it was held that if the structured approach of the ‘Improver’ questions was adopted when considering the Protocol, it was only the third ‘Improver’ question which needed to be answered. At the most, the answers to the first two questions provided shortcuts to the answer to the third question. Approaching the third question, Laddie J held in this case and in Telsonic AG’s Patent [2004] RPC 38, that putting the third ‘Improver’ question the opposite way round was more consistent with the guidance in Catnic. The question should therefore be “whether it would have been apparent to the skilled addressee from the wording of the claim that a limitation to exclude the variant could not have been intended by the patentee.”

Application of the Protocol questions

125.21

The Protocol questions are only guidelines for applying purposive construction to equivalents, as highlighted in Lord Hoffmann’s speech in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 : “When speaking of the ‘Catnic principle’, it is important to distinguish between, on the one hand, the principle of purposive construction which gave effect to the requirements of the Protocol, and on the other hand, the guidelines for applying that principle to equivalents, which are encapsulated in the Protocol questions. The former is the bedrock of patent construction, universally applicable. The latter are only guidelines, more useful in some cases than in others.” The judgment stated that the Protocol questions are useful in many cases, but they are not a substitute for trying to understand what the person skilled in the art would have understood the patentee to mean by the language of the claims.

125.22

The notion of strict compliance with the primary or conventional meaning in the third Protocol question was considered by Lord Hoffmann in Kirin-Amgen v Hoechst Marion Roussel Ltd [2005] RPC 9 to sit most comfortably with the use of figures, measurements, angles and the like, when the question was whether they allowed for some degree of tolerance or approximation. For example, in Catnic, a claim to a lintel having inter alia a support member “extending vertically” was held to have been infringed by otherwise identical lintels in which the support member was 6° or 8° from vertical, since this produced a negligible reduction in the vertical support provided by the member. There were also undoubtedly some cases, not involving figures or measurements, in which the question was whether a word or phrase was used in a strictly conventional or some looser sense.

125.23

However, the Protocol questions may be unhelpful in determining the extent of protection in rapidly-developing, high-technology fields. In these cases, a claim could, on its proper construction, cover products or processes which involved the use of technology unknown at the time the claim was drafted if the person skilled in the art would have understood the description in a way which was sufficiently general to include the new technology. Rather than consider the second Protocol question, which creates an ambiguity over whether “works in the same way” involves an assumption that the variant actually works at all (see 125.19), Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 held that if the claim could properly be construed in a way which was sufficiently general to include the new technology, the Protocol questions answered themselves. Difficulties in applying the Protocol questions also occur where there is no question of whether a word was being used in a strictly conventional or looser sense. In Kirin-Amgen, there was no suggestion that “an exogenous DNA sequence coding for erythropoietin” could have some looser meaning to include “an endogenous DNA sequence coding for erythropoietin”. Rather, the question was whether the person skilled in the art would have understood the invention as operating at a level of generality which made it irrelevant whether the DNA which coded for erythropoeitin was exogenous or not.

Extent of Protection and the Protocol: Summary

125.24

Lord Hoffmann held in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 that the determination of the extent of protection conferred by a European patent is an examination in which there is only one compulsory question, namely that set by article 69 and its Protocol: what would a person skilled in the art have understood the patentee to have used the language of the claim to mean? Everything else, including the Protocol questions, is only guidance to the judge trying to answer that question.

125.25

The principles of claim construction were summarised by Jacob LJ in Technip France SA’s Patent [2004] RPC 46 in paragraphs 41(a)-(k). These were approved by Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 apart from subparagraph (e), where Lord Hoffmann held that there is no presumption about the width of the claims when considering fairness to the patentee. In Mayne Pharma v Pharmacia Italia SpA [2005] EWCA Civ 137, Jacob LJ summarised these principles, but omitting subparagraph (e) as follows:

“(a) The first, overarching principle, is that contained in article 69 itself.

(b) Article 69 says that the extent of protection is determined by the terms of the claims. It goes on to say that the description and drawings shall be used to interpret the claims. In short the claims are to be construed in context.

(c) It follows that the claims are to be construed purposively - the inventor’s purpose being ascertained from the description and drawings.

(d) It further follows that the claims must not be construed as if they stood alone the drawings and description only being used to resolve any ambiguity.

(f) Nonetheless purpose is not the be-all and end-all. One is still at the end of the day concerned with the meaning of the language used. Hence the other extreme of the Protocol - a mere guideline - is also ruled out by article 69 itself. It is the terms of the claims which delineate the patentee’s territory.

(g) It follows that if the patentee has included what is obviously a deliberate limitation in his claims, it must have a meaning. One cannot disregard obviously intentional elements.

(h) It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context.

(i) It further follows that there is no general “doctrine of equivalents.”

(j) On the other hand purposive construction can lead to the conclusion that a technically trivial or minor difference between an element of a claim and the corresponding element of the alleged infringement nonetheless falls within the meaning of the element which read purposively. This not because there is a doctrine of equivalents: it is because that is the fair way to read the claim in context.

(k) Finally purposive construction leads one to eschew what Lord Diplock in Catnic called (at p.243) : ‘the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge’”.