The United Kingdom Supreme Court (UKSC) today handed down its judgment in the case of Actavis UK Limited and others v Eli Lilly and Company ([2017] UKSC 48) that has significantly changed the law of patent infringement in the UK.


Lilly is the proprietor of a patent that claims the use of pemetrexed disodium in the manufacture of a medicament for use in combination with vitamin B12 (and, optionally, folic acid) for the treatment of cancer. Actavis sought declarations of non-infringement for its proposed products which used (i) pemetrexed diacid, (ii) pemetrexed ditromethamine, or (iii) pemetrexed dipotassium in place of pemetrexed disodium. Actavis sought such declaration in respect of the UK, French, Spanish and Italian designations of Lilly's patent. The ability of the English courts to grant such declarations in respect of the foreign designations had been confirmed earlier in this action.

The High Court held that none of the Actavis products would directly or indirectly infringe the patent in the UK, France, Italy and Spain. The Court of Appeal allowed Lilly's appeal in respect of there being indirect infringement of the patent in each jurisdiction. Both parties were given permission to appeal to the UKSC.


The UKSC concluded that as a matter of ordinary language, it is clear that the only type of pemetrexed compound to which the patent claims expressly extends is pemetrexed disodium. The question that the UKSC then had to consider was how far one can go outside the wording of a claim.

The UKSC reviewed the relevant case law of the UK and other Convention states. In relation to the UK, those cases were the well-known cases of Catnic, Improver and Kirin-Amgen and the Improver/Protocol questions that arose from those cases. The UKSC has stated that the problem of infringement is best approached by addressing the following two issues:

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

If the answer to either of those questions is "yes" then there is infringement, otherwise there is not. The decision states that issue 1 self-evidently raises a question of interpretation, whereas issue 2 raises a question which would normally have to be answered by reference to the facts and expert evidence. The UKSC then criticises the approach taken in Catnic, Improver and Kirin-Amgen for effectively conflating the two issues and indicates that characterising the issue as a single question of interpretation is wrong in principle.

The UKSC went on to explain that treating issue 2 as one of interpretation will lead to a risk of wrong results in patent infringement cases and it will also lead to a risk of confusing the law relating to interpretation of documents. Accordingly, issue 2 is said to involve not merely identifying what the words in the 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.

Applying this new approach to the facts of this case, the UKSC confirmed that, in relation to the first issue, there was no doubt that the Actavis products do not infringe the patent as in no sensible way can pemetrexed diacid, pemetrexed ditromethamine or pemetrexed dipotassium be said to fall within the expression "pemetrexed disodium". However, it is the second issue that posed more difficulties of principle to the UKSC namely, what is it that makes a variation "immaterial"? While acknowledging that the Improver questions provided helpful assistance in answering that question, the UKSC has undertaken a critical explanation of questions 1 and 3 but has also reformulated question 2.

In relation to the first Improver question, the UKSC has now said that the emphasis of that question on how "the invention" works should involve the court focussing on "the problem underlying the invention", "the inventive core" or "the inventive concept". Terms such as this will be familiar to practitioners in other jurisdictions.

The UKSC found the second Improver question more problematic. Its view is that it places too high a burden on the patentee to ask whether it would have been obvious that the variant had no material effect on the way the invention works, given that it requires the addressee to figure out for himself whether the variant would work. To overcome this problem, the UKSC has determined that this question should be asked on the assumption that the notional addressee knows that the variant works. This new question should also apply to variants which rely on, or are based on, developments which have occurred since the priority date, even though the notional addressee is treated as considering the second question as at the priority date.

In relation to the third Improver question, the UKSC was satisfied with that question as long as it was properly applied. The court makes four points in relation to that. First, the "language of the claim" does not exclude the specification and all the knowledge and expertise which the notional addressee is assumed to have. Second, the fact that the language of the claim does not on any sensible reading cover the variant is not enough to justify holding that the patentee does not satisfy the third question. Third, it is appropriate to ask whether the component at issue is an "essential" part of the invention, but that is not the same thing as asking if it is an "essential" part of the overall product or process of which the inventive concept is a part. Fourth, when considering a variant which would have been obvious at the date of infringement rather than at the priority date, it is necessary to imbue the notional addressee with rather more information than he might have had at the priority date.

In an attempt to assist with interpreting their judgment, the UKSC expressed their new questions as follows:

  • Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?
  • 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?
  • 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 impact of these new questions and the new approach to assessing infringement of patents in the UK (and the consequences for the validity of those patents) will take time to become fully appreciated.

Prosecution History

The UKSC was also asked to consider the use of the prosecution file when considering the question of interpretation or infringement. It concluded that its current view was that such reference to the file would only be appropriate where (a) 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 (b) it would be contrary to the public interest for the contents of the file to be ignored.

In the present case, the UKSC did not consider that the file justified departing from its conclusion that the Actavis products infringed Lilly's patent.

Foreign law

The UKSC had to address issues relating to infringement in France, Italy and Spain. Those issues are to be the subject of a separate note.