In a decision that appears to have introduced a doctrine of equivalents for the first time, the UK Supreme Court has shifted the laws on patent infringement in Actavis v. Eli Lilly UK  UKSC 48. While this case represents a significant change in the UK, the decision actually brings the UK law closer to the rest of Europe and the US. The claims at issue involve 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. The old standard of claim interpretation in the UK was a strict one – a claim basically means what is says and there is only limited latitude for covering non-literal infringement. In a change from the old standard, the Actavis case set out a two-step test for deciding infringement:
- Does the variant infringe any of the claims as a matter of normal interpretation; and, if not,
- Does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial?[i]
Applying this new approach standard, Supreme Court confirmed that there was no literal infringement since pemetrexed diacid, pemetrexed ditromethamine or pemetrexed dipotassium are not literal equivalents of pemetrexed disodium. However, the Court did rule that the dipotassium achieved substantially the same result in substantially the same way as disodium. The Court ruled therefore, that the dipotassium was an immaterial variant and infringed. In aiding interpretation of the judgment, the Court clarified the two-step test 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?[ii]
Interestingly, the Court suggested it would be appropriate to refer to the prosecution history if the question of infringement was truly unclear in light of the specification and claims, and if the file wrapper clearly and unambiguously resolves the issue. In this case, the Court was not persuaded that an amendment to explicitly recite disodium in the claim was in response to an added matter objection. Thus, while US practitioners have been mindful of statements made during prosecution for some time, the Actavis decision highlights their importance in the UK as well.