In the most important decision on patent infringement for over a decade, the UK Supreme Court has confirmed that UK law does provide for a doctrine of equivalence when determining the scope of patent protection. The case – Actavis UK Limited v. Eli Lilly & Company [2017] UKSC 48 – concerned the use of the chemical pemetrexed for the treatment of cancerous tumours. In particular, the relevant claims were directed to the use of a combination of a salt of pemetrexed, pemetrexed disodium, in combination with vitamin B12 (and optionally, folic acid). The combination avoided the otherwise damaging side-effects of pemetrexed that prevented the therapeutic use of pemetrexed alone.

Instead of pemetrexed disodium, Actavis’s products used pemetrexed diacid, pemetrexed ditromethamine, or pemetrexed dipotassium. The drugs were administered intravenously, in practice being dissolved in saline prior to administration. The key question was whether the scope of protection of patent claims directed to pemetrexed disodium extended to the pemetrexed products used by Actavis. The first instance court and the Court of Appeal had both held that they did not, as the patent claims were limited to the disodium salt. A secondary question, raised by Actavis in a cross-appeal, was whether Actavis’s products indirectly infringed the patent, as had been found by the Court of Appeal.

Lord Neuberger, the President of the Supreme Court, wrote the Court’s judgment, which was handed down on 12 July 2017. The key legislation was the Protocol on the Interpretation of Article 69 of the European Patent Convention as amended in 2000 (“EPC 2000”). Article 1 of the Protocol requires a balance to be drawn between a strict, literal interpretation of patent claims and the use of patent claims merely as a guideline. The balance must provide fair protection for patentees and reasonable certainty for third parties. Article 2 of the Protocol, which was added by the EPC 2000, requires that “due account shall be taken of any element which is equivalent to an element specified in the claims”.

Lord Neuberger considered that the question of infringement by variants was best approached by considering two issues: (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? If the answer to either question is “yes”, there is an infringement. Such an approach would take equivalents into account but limit their ambit to immaterial variations from the invention. In Lord Neuberger’s opinion, the previous approach direct by the Supreme Court in 2005 in the case of Kirin-Amgen conflated these two issues, and treated them both as issues of interpretation of the claim language, when in fact issue (ii) requires not just consideration of the interpretation of the language but also consideration of the extent (if any) to which the scope of protection should extend beyond that meaning.

The Court accordingly favoured the application of the three “Improver” questions (dating from a 1990 case), that had prior to Kirin-Amgen been routinely applied by the UK courts, but considered that they needed to be re-formulated, as follows:

  1. 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, ie the inventive concept revealed by the patent?
  2. 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?
  3. 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?

In order to establish infringement in a case where there was no literal infringement, a patentee would have to establish that the answer to the first two questions was “yes” and that the answer to the third question was “no”.

Applying these re-formulated questions to the facts of the case, the Supreme Court held that the answers were indeed, “yes”, “yes” and “no”. Once dissolved it was the pemetrexed anion that was the active ingredient; it did not matter what the cation was as long as the product dissolved. The skilled person would not know in advance what the solubility of any pemetrexed salt would be but this was a matter of routine testing and he or she would expect to be able to find a salt of appropriate solubility. On knowing that a particular salt worked, the skilled person would know that it would work in the same way as the disodium salt. Finally, the Court did not think that the skilled person, looking at the patent specification as a whole, would believe that the patentee intended to limit the scope of protection of the claims to just the disodium salt. The examples all used the disodium salt and the skilled person would understand that that was why the claims were so limited but that did not mean that the patentee intended to exclude infringement by any other salt.

The Supreme Court also considered the application of the patent’s prosecution history, holding that the circumstances in which it would be appropriate for a court to have regard to the prosecution history were limited and would only be appropriate if either the point at issue was truly unclear or it would be contrary to the public interest to exclude the prosecution history.

On the question of indirect infringement, the Supreme Court agreed with the Court Appeal that Actavis would be liable for indirect infringement (even if there had been no direct infringement), as Actavis knew, or it was obvious in the circumstances, that ultimate users would dissolve the Actavis products in saline, which would result in a solution containing both sodium cations and pemetrexed anions, in other words a solution that contained pemetrexed disodium.

Finally, the Supreme Court held that its conclusions on infringement would also apply under French, Italian and Spanish law.

This ground-breaking decision broadens the scope of protection for patents in the UK and will be welcomed by many patentees. It confirms that immaterial variants will infringe, even if the literal claim language does not cover them. Conversely, this development of the law, especially if applied broadly by the lower courts, will inevitably create greater uncertainty for potential infringers, as they will not be able to design around a patent by taking a strict interpretation of the language of the claims.

The Supreme Court’s judgment also aligns UK law very closely with the approaches taken to variants by the German and Dutch courts. It is accordingly likely that the new Unified Patent Court, currently expected to commence operation in 2018, will adopt a very similar approach to claim construction and patent infringement.