INTERPRETING PATENT CLAIMS: SOME THOUGHTS ON THE UK KIRIN-AMGEN DECISION

• Author: Paul QUAN Kaih Shiuh LLB (Hons) (National University of Singapore). TEO Guan Siew LLB (Hons) (National University of Singapore).
• Published date: 01 December 2006
• Date: 01 December 2006

In patent infringement cases, what falls to be determined is where the rights of the patentee end and where non-infringing use for third parties begin. Invariably, this involves ascertaining the scope and ambit of the patent claim. This article articulates some thoughts, both generally and in the specific context of Singapore, on the recent House of Lords’ pronouncements in Kirin-Amgen Inc v Hoechst Marion Roussel Limited[2005] RPC 9 on patent claim interpretation.

I. Introduction

1 For intellectual property rights (“IPRs”) to be meaningful and not ring hollow to rights-owners, the ambit and scope of these rights cannot be given an unduly restrictive interpretation, which would otherwise result in mere fig-leaf protection. The length and width of protection have to be sufficiently attractive to encourage intellectual property owners to go public with and seek protection for their intellectual property, and to eventually part company with their intellectual property when the protection period expires and falls into the public domain. At the same time, an overly generous interpretation that results in wide and indeterminate IPRs can be ill afforded. IPRs are, by their very nature, true property rights, and they must therefore possess

the quintessential hallmark of certainty.1 The ambit and scope of IPRs have to be certain so that third parties “know the exact boundaries of the area within which they will be trespassers”,2 and can then reasonably be expected to chart their course to avoid infringing upon those rights. The proper interpretation of the ambit of IPRs therefore involves, understandably, a delicate balancing exercise.

2 This article is concerned with that exercise in the specific context of patent law, which largely seeks to protect inventions. To determine whether there is patent infringement, one must first determine the scope of the claimed invention, which in turn involves interpreting the patent claims. The patent claims are the means by which the patentee informs those skilled in the art the extent of the monopoly that he is claiming in respect of his invention, by defining clearly and with precision the essential features of that invention for which he is seeking protection.3

3 This article focuses on the interpretation of patent claims, and the recent House of Lords decision in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd4 in that regard. Part II first provides a general overview of the law governing patent claim interpretation in the UK, up until Kirin-Amgen. Part III then discusses some aspects of the Kirin-Amgen decision, and the discussion follows on in Part IV but from a local perspective.

II. Overview

4 Central to modern-day patent claim interpretation in the UK is arguably s 125 of the Patents Act 1977,5 which in turn is modelled after Art 69 of the European Patent Convention (“EPC”).6 Section 125(1) of

the Patents Act 1977 essentially provides that an invention for a patent is to be defined by the patent claim read with the rest of the specification:

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 drawing contained in that specification, and the extent of the protection conferred by a patent or application for a patent shall be determined accordingly.

Article 69(1) of the EPC states this in simpler and clearer terms:

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.

5 Section 125(3) of the Patents Act 1977 goes on to state that the Protocol on the Interpretation of Art 69 of the European Patent Convention (“the Protocol”) shall apply for the purposes of s 125(1) of the Patents Act 1977 as it applies for the purposes of Art 69 of the EPC. The Protocol provides some guidance as to how Art 69 of the EPC, and in turn s 125(1) of the Patents Act 1977, should be construed:

Article 69 should not be interpreted in the sense that the extent of the protection conferred by a European Patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Neither should it be interpreted in the sense that the claims serve only as a guideline and that the actual protection 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.

It follows that interpreters of a patent claim should not, on the one hand, give the wordings of the claim their strict literal meaning, and should read the claim together with the rest of the specification. The rest of the specification should not be employed only when ambiguity in the claim exists. On the other hand, the rest of the specification cannot be used to enlarge the claim beyond what the patentee actually intended. Article 69 of the EPC envisions a measured approach to patent claim interpretation, which ultimately aims to provide fair protection for the patentee, whilst also affording reasonable certainty to third parties.

6 Prior to the advent of the Patents Act 1977 and the EPC, the common law governed patent claim interpretation, and was typified by a strict interpretation of the claim.7 What was not claimed was disclaimed.8 The limits of what was claimed fell to be determined by the language of the claim and not elsewhere.9 Thus, a patentee who described an invention obtained no monopoly unless he did so in the claim.10 The words of the claim were given their literal or textual meaning, regardless of the context and background in which they were used. Unless the words were ambiguous, the court would not otherwise read in words or seek recourse to the rest of the specifications to extend or narrow the scope of the monopoly set by the plain words of the claim. In the words of Viscount Radcliffe,11 the patentee had committed himself to the unequivocal description of what he claimed to have invented, and must submit to be judged by his own action and words (having been assumed to have carefully selected the wording of the claim to put him in as strong a position as his expert advisers thought attainable or advisable).

7 It was not until the seminal House of Lords decision in Catnic Components Limited v Hill & Smith Limited12 that the approach to interpreting patent claims underwent a sea change. Lord Diplock advocated a “purposive construction” of patent claims, where the crucial question that had to be answered by a court when interpreting patent claims was:13

[W]hether 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. [emphasis in original]

He then elaborated on how that question could be answered:14

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.

8 Subsequently, the Catnic approach to interpreting patent claims was further explained by Hoffmann J (as he then was) in Improver Corporation v Remington Consumer Products Limited.15 Hoffmann J formulated the Catnic approach with a convenient set of three questions (“the Improver questions”):16

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

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

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

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

On the other hand, a...