This article originally appeared in the PLG journal in December 2017.
In a landmark decision, Actavis v Eli Lilly  UKSC 48, the UK Supreme Court has re‐steered the law of patent infringement in the UK, stating that there is a doctrine of equivalents, and expressly permiting recourse by the courts to the prosecution file in appropriate limited circumstances.
As a result of the Supreme Court's ruling, Actavis' proposed pemetrexed medicines were found to infringe, directly and indirectly, Eli Lilly's European patent no. 1,313,508 ("EP '508"), which has claims directed to pemetrexed disodium in combination with vitamin B12 for cancer treatment.
Background to the claim
Actavis sought from the UK court a declaration of non‐infringement in respect of a number of pemetrexed compounds used together with vitamin B12 for cancer treatment. The pemetrexed active ingredient in those products ("the Actavis products") was (a) pemetrexed diacid (b) pemetrexed ditromethamine, or (c) pemetrexed dipotassium. EP '508 contained the following claim:
"1. Use of pemetrexed disodium in the manufacture of a medicament for use in combination therapy for inhibiting tumour growth in mammals wherein said medicament is to be administered in combination with vitamin B12 or a pharmaceutical derivative thereof [which it then specifies]."
Claim 1 was in Swiss form (i.e. use of X in the manufacture of a medicament for the treatment of Y). Claim 12 was, essentially, to the same subject matter but in purpose‐limited product form (i.e. X for use in the treatment of Y). The form of the claim language was not material to the outcome of the dispute and the Supreme Court's reasoning focused upon claim 1.
Three famous decisions have developed and defined the law on patent infringement in the UK in recent decades: Catnic Components Ltd v Hill & Smith Ltd  RPC 183, Improver Corpn v Remington Consumer Products Ltd  FSR 181 and Kirin‐Amgen Inc v Hoechst Marion Roussel Ltd  RPC 9.
For the last decade, the most influential decision has been that of the House of Lords in Kirin‐Amgen, in which Lord Hoffmann said, essentially, that issues of infringement could be resolved by adopting a 'purposive' construction to the language of the patent claim, so giving effect to "what the person skilled in the art would have understood the patentee to be claiming".
The role of the House of Lords as the highest appeal court has since ended; the Supreme Court of the UK has, since 1 October 2009, been the highest court of appeal for all civil law cases in the UK. Now, in Actavis UK Limited & Ors v Eli Lilly and Company  UKSC 48 (12 July 2017), the leading Justice of the current generation, Lord Neuberger (with the agreement of the other four Justices), respectfully rowed back from Lord Hoffmann's judgment in Kirin‐Amgen.
In the Supreme Court, Lord Neuberger went back to first principles, beginning with the legislative provisions, the critical text being that of Article 69 of the European Patent Convention (EPC) and the Protocol on its interpretation.
This, said Lord Neuberger, meant that ():
"…a problem of infringement is best approached by addressing two issues, each of which is to be considered through the eyes of the notional addressee of the patent in suit, i.e. the person skilled in the relevant art. Those issues are: (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 issue is "yes", there is an infringement; otherwise, there is not."
Lord Neuberger explained that issue (i) self‐evidently raises a question of interpretation, whereas issue (ii) raises a question which would normally have to be answered by reference to the facts and expert evidence. The difficulty with Lord Hoffmann's approach in Kirin‐Amgen was that it conflated the two issues. This was wrong in principle and, therefore, could lead to error. Issue (ii) 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.
Lord Neuberger explained that issue (i), the question of whether the variant infringes any of the claims as a matter of normal interpretation, requires the application of the normal principles of interpreting documents. In the UK these were recently affirmed by Lord Hodge in the Supreme Court in Wood v Capita Insurance Services Ltd  UKSC 24 (paragraphs 8 to 15).
The authors note that the court is required to establish the skilled addressee's understanding of what the author of the patent meant by using the words of the claim in the context of the specification. However, and importantly, this does not involve consideration of the Improver questions, either as originally phrased or as re‐formulated by Lord Neuberger.
Issue (ii) poses more difficulties of principle: what is it that makes a variation “immaterial"? In this context, Lord Neuberger considered that the three questions formulated by Hoffmann J (as he then was) in Improver (which pre‐dated Kirin‐Amgen), provide helpful assistance but needed some reformulation. He proceeded to undertake the reformulation, saying that the reformulated questions remain only guidelines, not strict rules, and that they may also sometimes have to be adapted to apply more aptly to the specific facts of a particular case. The reformulated questions are:
- 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?
Lord Neuberger clarified: "In order to establish infringement in a case where there is 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"."
Lord Neuberger explained that in the first reformulated question, the emphasis is on how "the invention" works. The court should focus on "the problem underlying the invention", the "inventive core" or "the inventive concept" as it has been variously termed in other jurisdictions.
Compared with the original first Improver question, Lord Neuberger's re‐wording crucially shifts the focus away from assessing the invention as set out in the claims towards identifying the inventive concept of the patent.
Lord Neuberger explained that the second reformulated question should be asked on the assumption that the notional addressee knows that the variant works to the extent that it actually does work. He considered this a fair basis on which to proceed in light of the factors identified in article 1 of the Protocol and the fact that the notional addressee is told (in the patent itself) what the invention does.
Lord Neuberger noted that this approach was consistent with that taken by the German, Italian and Dutch courts.
Compared with the original second Improver question, this is a lowering of the burden on the patentee seeking to establish infringement. In the original question the patentee needed to establish that it would have been obvious, at the date of the publication of the patent to a reader skilled in the art, "that the variant has no material effect". This required the addressee to figure out whether the variant would work.
Lord Neuberger said that the facts of the Actavis v Eli Lilly case illustrated why this was too strict a test: because a chemist would not be able to predict the effect of a substitution for the sodium counter‐ion without testing at least the solubility of the active ingredient in the Actavis products, it was not possible to predict in advance whether any particular counter‐ion would work. However, salt screening was a routine exercise in determining suitability, and the chemist would be reasonably confident that he would come up with a substitute for the sodium counter‐ion. In those circumstances, given that the inventive concept of the patent was the manufacture of a medicament which enabled the pemetrexed anion to be administered with vitamin B12, the application of the original second improver question failed to accord "a fair protection for the patent proprietor" as required by article 1 of the Protocol.
Lord Neuberger also said that the reformulated second question should apply to variants which rely on, or are based on, developments that have occurred since the priority date, even though the skilled addressee is treated as considering the second question as at the priority date. There is also no requirement for the variant not to be inventive - it may be that the infringer is entitled to a new patent, but that is "no reason why the variant should not infringe the original patent".
Regarding the third reformulated question, Lord Neuberger made a number of points:
- Although the language of the claim is important, consideration is not excluded of the specification of the patent and all the knowledge and expertise which the notional addressee is assumed to have.
- 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. In other words, the fact that the variant is not within the "normal interpretation" of the claim and so does not infringe pursuant to limb (i) does not prevent the skilled reader of the patent from concluding that the patentee did not intend that strict compliance with the literal meaning of the claim was necessary, and therefore from concluding that the variant infringes pursuant to the doctrine of equivalents.
(The authors note that this is common sense; if it were otherwise, it is difficult to imagine any scenario in which the doctrine of equivalents might be found to apply).
- It is appropriate to ask if 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 part. In Lord Neuberger's view, in the Improver case, Hoffmann J "may" have wrongly considered the latter question.
- When one is 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.
Proceeding to consider whether the Actavis products would infringe EP '508 pursuant to limb (ii), Lord Neuberger tentatively concluded that the doctrine of equivalents did indeed apply.
However, before deciding the point conclusively, he turned to the issues in the case regarding the prosecution history of EP '508.
Recourse to the prosecution file
In support of its case of noninfringement, Actavis relied upon the prosecution history of the patent. This gave rise to a question of general application: whether, and if so when, is it permissible to have recourse to the prosecution of a patent when considering whether a variant infringes that patent?
Lord Neuberger concluded that the UK courts should adopt a "sceptical, but not absolutist, attitude" to a suggestion that the contents of the prosecution file of a patent should be referred to when considering a question of interpretation or infringement, along substantially the same lines as the German and Dutch courts. He explained that his "current view" was that reference to the file 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."
Lord Neuberger said that the second type of circumstance "would be exemplified by a case where the patentee had made it clear to the EPO 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".
Turning to the prosecution file of EP '508, the examiner had rejected claims using "antifolate" terminology for reasons of disclosure and clarity (Articles 83 & 84 EPC). In response, Lilly proposed amended claims using the word "pemetrexed". The examiner objected to these claims on the basis of added matter (Article 123(2) EPC), saying there was no basis for such terminology because pemetrexed was a distinct compound from pemetrexed disodium. Reserving its position, Lilly filed new claims using "pemetrexed disodium" wording and the application proceeded to grant.
Lord Neuberger said that, although it was unnecessary to decide the issue, in his view the examiner had been wrong to take the view that the patent should be limited to pemetrexed disodium because the teaching of the patent did not expressly extend to any other antifolates. However, even if the examiner was right or at least justified in taking the stance that he did, this did not have any bearing on the question of whether any pemetrexed salts other than pemetrexed disodium should be within the scope of the patent pursuant to the doctrine of equivalents. Lord Neuberger said ():
"The whole point of the doctrine is that it entitles a patentee to contend that the scope of protection afforded by the patent extends beyond the ambit of its claims as construed according to normal principles of interpretation."
So the contents of the prosecution file did not justify departing from the preliminary conclusion that the Actavis products directly infringed claim 1.
Conclusion on direct infringement
Accordingly, Lord Neuberger concluded that the Actavis products would directly infringe the UK designation of EP '508.
Finally, Lord Neuberger confirmed the conclusion of the Court of Appeal (over turning Arnold J) that the Actavis products also indirectly infringed the UK designation of EP '508.
The expression "pemetrexed disodium" was not limited to the solid, or crystalline, chemical. Accordingly, even if pemetrexed dipotassium would not of itself infringe if it was administered with vitamin B12, at least provided that the ratio of sodium ions to pemetrexed ions was at least 2:1, there would be infringement when it was administered in saline solution, because the solution would contain pemetrexed disodium.
The UK Supreme Court's judgment in Actavis v Eli Lilly marks the most significant development in UK patent law for decades.
Apparently aligning the UK law of infringement more closely with that of Germany, the (re‐) introduction of a doctrine of equivalents can be expected to assist patent proprietors in defending their monopoly against immaterial variants, to reduce the incidence of inconsistent conclusions on infringement as between the courts of the UK and those of other major EPC jurisdictions, and to smooth the way for the harmonisation of the law regarding infringement expected with the coming into force of the Unified Patent Court.
Also importantly for patentees, the existence of a doctrine of equivalents potentially provides greater wriggle room, when seeking an effective and meaningful scope of protection which is also justified by the level and scope of the invention disclosed.
The UK Supreme Court's decision is one, therefore, that should be considered without delay by inventors, patent attorneys, litigators and potential infringers alike.
If you enjoyed this article, please explore Gordon Harris' article titled Actavis v Eli Lilly - Should We Have Seen it Coming?.