The claims of a patent are sometimes thought of as being like a fence, which encloses and defines the scope of the monopoly granted by the patent. If so, the exact position of the fence is often a key subject of contention in patent litigation. In a judgment handed down on 12 July 2017 the Supreme Court clarified the circumstances in which the monopoly may be widened beyond the normal interpretation of the claim to cover variants which have no material effect on the way the invention works (sometimes referred to as equivalents). This important decision is likely to make it more difficult for competitors to ‘work around’ a patent.
The case - Actavis UK Ltd and others v Eli Lilly and Company - is the latest, and presumably final, chapter in a protracted legal battle arising out of Actavis’s wish to enter the market with a generic version of Lilly’s successful anti-cancer treatment, Alimta, following expiry of Lilly’s basic patent for pemetrexed (December 2015). Alimta is protected by a later Lilly patent (1 313 508) that relates to the use of pemetrexed disodium in combination with vitamin B12. It is this combination which allows pemetrexed to be used safely in the treatment of cancer without serious side effects.
Actavis sought declarations of non-infringement in an attempt to ‘clear the way’ for generic products equivalent to Alimta. Actavis’s products would substitute pemetrexed diacid, pemetrexed ditromethamine or pemetrexed dipotassium active ingredients (the ‘AIs’) instead of pemetrexed disodium. In this way they would avoid the express wording of the claim, which was limited to pemetrexed disodium. The parties agreed, however, that these substances worked in the same way – indeed, as pointed out by the Court of Appeal, Actavis would be granted marketing approval on the basis that its products were bioequivalent to Alimta. Lilly argued that these AIs were simply immaterial variants which were within the scope of protection of the claim and therefore constituted direct infringements. Actavis countered that their products fell outside the ‘fence’ and did not infringe. Actavis’s arguments on direct infringement prevailed both in the High Court and in the Court of Appeal. However, the Supreme Court disagreed, holding that there was indeed direct infringement. In so doing it relaxed and reformulated the test used by the UK courts to decide whether a variant infringes. It broadened the scope of protection of the patent in such circumstances and brought the test used in the UK courts more into line with that used in other important European patent jurisdictions.
What has changed?
A key change is that under the old test the variant would infringe if it would have been obvious to the skilled addressee, reading the patent at the time of publication, that the variant would have no material effect on the way the invention worked. This meant that the skilled addressee must have been able to work out for him/herself on the basis of the patent and common general knowledge at that time whether the variant would work. Under the reformulated test, by contrast, the addressee is treated as knowing that the variant achieves the same result as the invention. The question is then whether, knowing this, it would have been obvious to them that it did so in substantially the same way as the invention. This means, among other things, that variants may include new developments since the priority date. In the present case the new test meant that the court did not have to take into account the fact that the skilled reader would not know for sure that the new products would work in practice without testing them.
Relevance of the prosecution history
Actavis argued that the prosecution history of the patent should be taken into account in interpreting the claim. In its view the prosecution history made it clear that the claim was intended to be limited to pemetrexed disodium alone. While not excluding it entirely, the UK courts have long been sceptical about using the prosecution history in this way. The Supreme Court confirmed this approach. Lord Neuberger, giving the decision of the court, said that while it would be arrogant to exclude the existence of any other circumstances, reference to the file would only seem to be appropriate in two cases: either a) a point was truly unclear in the patent and the file would unambiguously resolve it; or b) it would be contrary to the public interest not to take the contents of the file into account. An example of the latter would be where the patentee had made it clear to the EPO that they were not seeking to contend that the patent, if granted, would extend to the sort of variant which was now claimed to infringe. Reference to the prosecution file in the present case made no difference to the outcome.
The impact of the decision in practice
The Supreme Court’s decision highlights that the scope of protection of a patent can go beyond the express wording of the claim, even where there is no ambiguity in the wording. Although patent attorneys generally strive to cover equivalents expressly, the decision will be welcomed by patent owners as providing a good fall-back position where the express wording of the claims is not broad enough (as here). It may be seen as fair in that it protects the inventive concept. For competitors, though, the decision can be seen as raising further uncertainty about how ‘close to the wind’ they can sail.
The decision has been seen by many as introducing a “doctrine of equivalents” into UK patent law, something that UK judges have resisted in the past. A point emphasised by Lord Neuberger’s analysis is that it is not a question of whether the claim can be interpreted to include the variant – the variant extends the scope of protection given by the patent beyond the normal interpretation of the wording of the claim. This approach seems likely to lead to broader protection.
The Court’s guidance on the use of the prosecution history is welcome. However, the question of what will be regarded as contrary to the public interest in particular may require further development by the courts in future.
For the parties themselves the Supreme Court’s decision amounts to a victory for Eli Lilly, the patentee. Although, given the Court’s decision on direct infringement the point did not arise, the Supreme Court upheld the Court of Appeal’s decision that, on the particular facts, there would also be indirect infringement.