24 July 2017

Doctrine of equivalents & prosecution history - UK Supreme Court clarifies


The Supreme Court of the United Kingdom has recently passed its judgment in the case of the Actavis Vs. Eli Lilly and Company , on 12th July, 2017. This judgment has very wide ramifications on some of the most critical principles of UK Patent Law. Apart from clarifying the applicability of the doctrines of equivalents, the judgment also provides a clear picture as to when prosecution history can be used in construing claims of granted patent.



The judgment has been issued on an appeal and cross-appeal filed by the parties from the decision of the Court of appeal. The suit was initially initiated by Eli Lilly against Actavis for patent infringement. The trial court decided none of the products in question directly or indirectly infringe the patent. On appeal, the Court of appeal agreed that there would be no direct infringement, but held that there would be indirect infringement. Both parties appealed this decision to the United Kingdom Supreme Court, which held that Actavis directly infringe the patent. In the course of issuing this judgment, the UK Supreme Court built up and clarified the position of law espoused by the House of Lords in Kirin-Amgen Inc v. Hoechst Marion Roussel Ltd. (2005) RPC 9.



After considering prior judgments in the United Kingdom on claim construction, as well as approach used by courts in other European countries, the United Kingdom Supreme Court held that infringement analysis, when dealing with an allegedly infringing product that is a variant of what is covered by the claims, is best approached by addressing two issues, each of which is to be considered through the eyes of the person skilled in the relevant art:

   i.     does the variant infringe any of the claims as a matter of normal interpretation; and, if not,
  ii.     does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial?

The UK Supreme Court also observed that the judgment in Kirin-Amgen Inc. impermissibly conflated the two questions because question 1 pertains to the interpretation of the claim, whereas question 2 would normally have to be answered by reference to the facts and expert evidence. In particular, question 2 involves not merely identifying what the words of a claim would mean in their context to the notional addressee, but also considering the extent, if any, to which the scope of protection afforded by the claim should extend beyond that meaning.

The UK Supreme Court, thereafter, went on to explain how the second question is to be answered in any given case. While the Court felt that the test propounded in Improver Corp. seems best suited, it required re-formulation. After analyzing this matter further, the Court held that the following three re-formulated factors would provide guidance on how the second question is to be answered:

   i.     Notwithstanding that it is not within the literal meaning of the relevant claims(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, ie the inventive concept revealed by the patent?
  ii.     Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?
  iii.     Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?

The fundamental re-formulation by the Court was with respect to the second factor noted above. Previously the second factor required an assessment of whether the variant having no material effect would have been obvious to a reader skilled in the art, at the date of publication of the patent. The UK Supreme Court believed that this imposed too high a burden on the patentee and therefore, did not offer a fair protection for the patentee. Accordingly, the Court revised the second factor to focus more on the results achieved by the variant. Importantly the Court clarified that this second factor should also apply to variants which rely on, or are based on, developments which have occurred since the priority date.

Finally, on the issue of prosecution history, the Supreme Court affirmatively reiterated the House of Lord’s decision in Kirin-Amgen Inc. , which discouraged the use of the patent office file during claim construction. However, in the Court’s view, it is appropriate to adopt a skeptical, but not absolutist, attitude to the use of the prosecution history. In the Court’s judgment, reference to the prosecution history would only be appropriate where (i) the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point, or (ii) it would be contrary to the public interest for the contents of the file to be ignored.

With regard to the second scenario noted above, the Court also observed that it would apply to a case where the patentee had made it clear to the patent office that he was not seeking to contend that his patent, if granted, would extend its scope to the sort of variant which he now claims infringes the patent.



The judgment of the UK Supreme Court definitely provides important guidance on the extent of applicability of the doctrine of equivalents in the United Kingdom as well as extent to which prosecution history can be used in claim construction. The re-formulation of the three factor test from improver corp. is interesting to say the least. Without a doubt the re-formulation provided by the Court appears to present a more balance protection to patentee.

The implications on India cannot be ignored. In Roche v. Cipla and Merck v. Glenmark , the Hon’ble Delhi High Court has recognized the application of UK jurisprudence in the Indian context and in particular has applied the House of Lord’s decision in Kirin-Amgen Inc.. Indian Courts have otherwise, directly or indirectly, suggested their preference to consider UK jurisprudence on matters where Indian jurisprudence is lacking, though it is not strictly resolved to only UK jurisprudence. Thus, these clarifications provided by the United Kingdom Supreme Court is likely to have significant implication in future patent law jurisprudence in India.



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