UK Patent Equivalents, Exclusions and Estoppel – where are we now?

July 2017

A 5 year battle between Eli Lilly (Lilly) and Actavis centred on Lilly’s patent for the use of pemetrexed disodium for cancer therapy, has culminated in a decision from the UK Supreme Court, allowing Lilly’s appeal and deciding that Actavis' Products directly infringe Eli Lilly's patent in the UK, France, Italy and Spain.  The Court also dismissed Actavis' cross-appeal on the basis that if its products did not directly infringe, they would indirectly infringe to the extent held by the Court of Appeal.  Full judgment here.

The appeal looked particularly at the issue of the correct approach to the interpretation of patent claims, and the requirement of the European Patent Convention 2000 (EPC) to take account of so-called equivalents.  It also raised the issue of the extent to which it is permissible to make use of the prosecution history of a patent when determining its scope.

The decision is significant because of the approach to determining scope of protection conferred by the patent; it could be seen as a more pro patentee approach that in previous UK cases.  The UK Courts have historically taken an approach of “purposive construction” (Kirin-Amgen [2005] RPC 9), meaning that the claim language chosen was usually of critical importance, with the specification being a document in the words of the patentee’s own choosing, usually chosen on skilled advice.  However, in this case, Lord Neuberger has stated that it is very unlikely that the notional addressee would have concluded that the patentee was intending to specifically exclude certain equivalents (used in the Actavis Products) from the scope of protection by the wording of the claim. 


Pemetrexed as a cancer treatment has been marketed by Lilly or its subsidiaries under the brand name Alimta since 2004.  It was protected by a basic patent that has been extended by SPCs which expired in December 2015.  Lilly also owns European Patent No. 1 313 508 (the Patent), which does not expire until June 2021, for the use of pemetrexed disodium in combination with vitamin B12 or a pharmaceutical derivative thereof.

Actavis’s proposed products involved pemetrexed compounds being used together with vitamin B12 for cancer treatment. However, rather than pemetrexed disodium, the active ingredient in the Actavis Products were (a) pemetrexed diacid, (b) pemetrexed ditromethamine, or (c) pemetrexed dipotassium.  In other words, rather than including the disodium salt referred to in claim 1 of the Patent, the Actavis Products include as the active ingredient (a) pemetrexed itself (ie the free acid), or pemetrexed with the hydrogens on the two -CO2H units replaced by (b) tromethamine, or (c) potassium.  Actavis contended that, because they intend to use products which did not include pemetrexed disodium, the claims of the Patent, which are expressed as involving the use of pemetrexed disodium, would not be infringed. 

In 2014 Mr Justice Arnold held that Actavis' proposed products would not amount to direct or indirect infringement and in 2015 the Court of Appeal upheld the High Court decision regarding direct infringement, but reversed the decision on indirect infringement, in so far that is the that if the Actavis products were reconstituted/diluted in a saline solution they would contain sodium ions in a ratio that would fall within the Patent claims and thus the supply of Actavis's Products would amount to indirect infringement.

The Supreme Court Appeal

The Supreme Court case specifically concerned whether the three products manufactured by Actavis would infringe the Patent and its corresponding designations in France, Italy and Spain, either indirectly under s 60(2) of the Patents Act 1977 (the matter for appeal) or directly under a proper interpretation of Article 69 of the Europe Patent Convention 2000 (the matter for cross-appeal).

The Supreme Court unanimously allowed Lilly’s appeal and held that the Actavis products would infringe the Patent in the UK, and in France, Italy and Spain.  Actavis’ cross-appeal was unanimously dismissed, so that, if its products would not directly infringe, they would indirectly infringe as held by the Court of Appeal in 2015.

In reaching its decision, the Supreme Court said in these circumstance, the Protocol on the Interpretation of article 69 [EPC] as amended in 2000 was “crucial to Lilly’s contention that the scope of protection afforded by the Patent extends to the Actavis products”.  Specifically, two points were clear from the Protocol.

The first, was that the scope of protection afforded to a patentee is not to be limited by the literal meaning of the claims.  The second was that it was apparent from article 2 that there is at least potentially a difference between interpreting a claim and the extent of the protection afforded by a claim, and, when considering the extent of such protection, equivalents must be taken into account.  However, it was noted that no guidance is given as to precisely what constitutes an equivalent or how equivalents are to be taken into account.

Lord Neuberger, stated that on the first point, according to normal principles of interpretation, the Actavis products would not infringe the Patent.  But the second point, which raised the issue of equivalents, posed a more difficult question of principle.

Three reformulated “Improver questions”

To consider how it was possible to go outside the wording of a claim to enable a patentee to enjoy protection against products or processes which are not within the ambit of the actual language, three significant UK cases and a number of significant cases decided in the courts of other EPC states were reviewed.

Considering Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183, Improver Corpn v Remington Consumer Products Ltd [1990] FSR 181 and Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 as well as the approach in the courts of other EPC states, the Supreme Court expressed in its own words, a reformulated version of the three “Improver questions”:

“In doing so, it is right to emphasise, as Lord Hoffmann did in Kirin-Amgen [2005] RPC 9, para 52, that these questions are guidelines, not strict rules (as indeed the Oberlandesgericht indicated in Case No 6 U 3039/16, when saying that it was “generally” true that “three requirements must be met”). While the language of some or all of the questions may sometimes have to be adapted to apply more aptly to the specific facts of a particular case, the three reformulated questions are as follows:

i)                   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?

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?

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”.”

The Decision

Over turning the 2015 Court of Appeal decision, it was held that the Actavis products directly infringed the Patent; the Court of Appeal had adopted an approach which placed “too much weight on the words of the claim” and not enough weight on article 2 of the Protocol.

Lord Neuberger was in no doubt that the Actavis products would work in the same way as the invention: they all ultimately involved a medicament containing the pemetrexed anion and vitamin B12.  “In my view, application in the present case of the three questions just identified results in the conclusion that the Actavis products infringe. So far as the first question is concerned, there can be no doubt but that those products work in the same way as the invention: they all ultimately involve a medicament containing the pemetrexed anion and vitamin B12. Thus, they achieve substantially the same result in substantially the same way as the invention. Indeed, as in the Court of Appeal, Actavis realistically accept that the first question is to be answered yes.”

Once he or she knew that the Actavis products achieved substantially the same result as the invention, a notional addressee of the Patent would have thought it obvious that this was so, particularly as he or she would have regarded investigating whether pemetrexed free acid, pemetrexed ditromethamine or pemetrexed dipotassium (the Actavis Products) worked as a routine exercise.   It was very unlikely that the notional addressee would have concluded that the patentee could have intended to exclude any pemetrexed salts other than pemetrexed disodium from the scope of protection.  Direct infringement was also established under French, Spanish and Italian law.

On the effect of the prosecution history “estoppel” on the case, Lord Neuberger stated that consideration by the Courts of the contents of the prosecution file by a UK court “will only be appropriate in limited circumstances, particularly if they clearly resolve a genuine ambiguity in the patent or it would be contrary to the public interest to disregard the file”.  The contents of the file did not justify departing from the conclusion in this case, but the words of Lord Neuberger could well be used in future cases to expand the role of file wrapper estoppel in the UK. 

This update was prepared by HGF Partner Martyn Fish. If you would like further advice on this or any other matter please contact Martyn or your usual HGF representative, alternatively visit our Contact page to get in touch with your nearest HGF office.