The UK Supreme Court’s recent judgment in Actavis v Eli Lilly sets out a revised approach to assessing the scope of protection of patents. The new approach is likely to confer greater protection on patent owners, by providing that the protection afforded to a patent is not limited to the wording of the claims, but can extend to cover variants that fall outside the meaning of the claims. This decision may also make it easier for patent holders to defend invalidity counterclaims without prejudicing their arguments on infringement.

Background

Eli Lilly’s patent claimed the use of pemetrexed disodium in the manufacture of a medicament for use in combination with vitamin B12 for the treatment of cancer. Whilst the effect of pemetrexed disodium on cancerous tumours had been known for some time, the combination with vitamin B12 largely avoided the potentially fatal side-effects of pemetrexed when used alone. Actavis applied for a declaration of non-infringement in respect of three products that did not include pemetrexed disodium, but instead used pemetrexed itself or other pemetrexed salts.

The key issue on appeal to the Supreme Court was whether Actavis’ products fell within the scope of protection of the Eli Lilly patent. At first instance and before the Court of Appeal it was held that they did not. The Supreme Court disagreed and overturned the decisions of the lower courts on the basis that the approach to construing patent claims set out by the House of Lords in Kirin-Amgen v Hoechst and the guidelines set out in Improver v Remington were wrong.

The scope of protection is not limited to the wording of the claim

In Kirin-Amgen the House of Lords held that when determining the scope of protection afforded to a patent:

“[t]he question is always what the person skilled in the art would have understood the patentee to be using the language of the claim to mean. And for this purpose, the language he has chosen is usually of critical importance”.

Asking what the “person skilled in the art” (i.e. the person or group of persons who is or are likely to have a practical interest in the claimed invention) would understand the claim to mean was considered by the House of Lords in Kirin-Amgen to strike the appropriate balance between ensuring a fair level of protection for the patent proprietor and a reasonable degree of legal certainty for third parties. Such a balance, lying somewhere between the strict, literal meaning of the wording and a situation where the wording of the claims serve merely as a guideline, is required by the Protocol to Article 69 of the European Patent Convention. Kirin-Amgen has been the leading case on the interpretation of patent claims since the judgment was handed down in October 2004.

The Supreme Court in Actavis v Eli Lilly has now decided that it was wrong to consider the scope of protection of a patent as a single issue of interpretation and that the approach in Kirin-Amgen did not strike the right balance between the competing interests of protection for patent owners and certainty for third parties.

Lord Neuberger, with whom the other Supreme Court Justices agreed, held that a two stage analysis was required to determine whether a variant fell within the scope of protection of a claim:

1. Does the variant infringe any of the claims as a matter of normal interpretation (considered through the eyes of the person skilled in the relevant art)?
2. Does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial (again, considered from the perspective of the person skilled in the relevant art)?

In so holding, Lord Neuberger has established that the protection afforded to a patent extends beyond the meaning of the words used in the claim. According to Lord Neuberger, this is required by the Protocol to Article 69 of the European Patent Convention.

The principle that a variant outside the meaning of the words in the claim can nonetheless infringe is known as the “doctrine of equivalents”. The Supreme Court’s judgment rejects the decision in Kirin-Amgen that protection cannot extend beyond the wording of the claims. The Supreme Court reviewed the approach taken to variants in Germany, France, Italy, Spain and the Netherlands and by incorporating a “doctrine of equivalents” into English law brought the English legal position closer to the position in those other countries.

On the facts in Actavis v Eli Lilly it was clear that Actavis’ products did not fall within the meaning of the relevant claims as they did not include pemetrexed disodium. It was therefore necessary to consider whether they were infringing variants.

When will a variant infringe?

Whilst Lord Neuberger considered it to be clear from the Protocol to Article 69 that the scope of protection can extend beyond the actual language used (as interpreted through the eyes of the person skilled in the art), the Protocol does not make it clear how far from the wording of the claim it is possible to go. Mindful of the statements in Kirin-Amgen that “once the monopoly had been allowed to escape from the terms of the claims, it is not easy to know where its limits should be drawn”, Lord Neuberger sought to provide guidance to determine when a variant that falls outside the meaning of the words of the claim will nevertheless infringe as an “immaterial variant”.

He did so by reformulating the guidance provided in Improver v Remington as follows (emphasis added): 

“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?”

The Supreme Court’s reformulation of question ii) was significant to the outcome of this case. The High Court and Court of Appeal, applying the prior guidance from Improver, found that there was no infringement because it would not have been obvious to the skilled person that swapping pemetrexed disodium for the variant salts would have no material effect - it would not have been possible for the skilled person to predict whether the alternative salts would work.

Lord Neuberger, however, decided to reduce the burden imposed on the patent proprietor by providing that the person skilled in the art is assumed to know that the variant achieves substantially the same result - all that needs to be obvious is that it does so in the same way (in light of the knowledge that it works). Lord Neuberger found that the skilled person, knowing that Actavis’ products worked, would appreciate that they did so in the same way as the product described in the patent. He went on to find that Actavis’ products did infringe under the doctrine of equivalents.

Relevance of the patent prosecution file

Eli Lilly had, in fact, limited the claims during the course of prosecuting the patent by limiting the general term “antifolates” (a category that included pemetrexed itself and other pemetrexed salts) to solely pemetrexed disodium. This was done in response to an objection by the examiner at the European Patent Office. It was the examiner’s view that the disclosure in the patent only provided support for the use of pemetrexed disodium and therefore the claims would be invalid for insufficiency if they covered the wider group.

Lord Neuberger held that this history did not have any bearing on whether the scope of the patent covered other pemetrexed salts under the doctrine of equivalents. 

In the US “file wrapper estoppel” is a significant check on the doctrine of equivalents, as it limits a patent proprietor’s ability to assert that a variant is covered by the patent where the proprietor specifically limited the claim to exclude the variant during the course of prosecution. In Actavis v Eli Lilly Lord Neuberger propounded a quite different approach. He said that the UK courts should adopt a “sceptical, but not absolutist” attitude to a suggestion that the contents of the prosecution file should be referred to when interpreting a claim. Lord Neuberger said that his “current view” was that reference to the prosecution file would only be appropriate where:

1. the point at issue is truly unclear when considered on the basis of the claims and patent specification alone and the prosecution file unambiguously resolves the point; or
2. it would be contrary to the public interest to ignore the prosecution file.

Lord Neuberger was careful, however, not to exclude the possibility that the prosecution file may be relevant in other circumstances as well.

Whilst the Supreme Court’s judgment perhaps suggests a slightly more flexible approach to the relevance of the prosecution file, it is clear that the relevant circumstances are limited. Applicants for patents should, however, be aware that statements during the course of prosecution that the patent is not contended to cover a particular variant, may be referred to on public interest grounds if the patent proprietor seeks to enforce the patent in respect of that variant further down the line.

Further comment

The Supreme Court’s decision is helpful to claimants in patent infringement actions. Not only has the Supreme Court expanded the scope of the claims of a patent, but in distinguishing the scope of protection from the meaning of the claims, patent proprietors may in certain circumstances have more flexibility when defending counterclaims for invalidity. The decision likely makes it more difficult to design around a patent by making minor changes, as such products may be caught by the doctrine of equivalents as “immaterial variants”. Often little solace will be found in the prosecution file. 

An argument often made by defendants to a patent infringement action is that if the claim is broad enough to cover the alleged infringement, it is invalid. The difficulty for the claimant is that a narrow interpretation of a claim may assist in proving that the patent is valid, but when it comes to infringement a broad interpretation may be needed to cover the alleged infringement. A claimant must often tread a fine line to avoid being hamstrung by its own arguments as to how the patent should be interpreted.

However, by dividing the meaning of the words, on the one hand, and the scope of protection, on the other, Lord Neuberger appears to have given patent proprietors greater wiggle room. It now seems open to patent proprietors to argue for a narrow interpretation of the claim in order to save validity (even if that means the wording of the claim does not cover the alleged infringement), but that there is nonetheless infringement under the doctrine of equivalents. It may also be possible for patent proprietors to narrow their claims in order to defend invalidity arguments, but argue that the infringement is covered by the doctrine of equivalents if the amendment takes the alleged infringement outside the words of the claim.

Whilst Lord Neuberger didn’t directly follow any of the approaches to equivalents in other jurisdictions. The Supreme Court’s decision brings English law in this area closer to that of other members of the European Patent regime, reducing the risk of inconsistent judgments across jurisdictions in respect of the same products.