July 17, 2017

UK Supreme Court Overturns Existing Case Law to Broaden the Scope of Patent Protection


The UK Supreme Court has overturned existing case law to, for the first time, formally recognise a "doctrine of equivalents", resulting in a broader scope of patent protection under UK law. This new approach is more patentee-friendly and brings the UK into closer alignment with courts elsewhere in Europe and in the US.

Historically the English courts have held that the wording of the claim is decisive when determining whether a patent is infringed, resulting in a relatively narrow scope of protection. The Supreme Court held that this approach placed too much weight on the words of the claim and did not provide fair protection for patent holders. Fair protection requires a broader scope of protection, extending beyond the wording of the patent claims to also cover products which are technically equivalent. In the case at hand, the Supreme Court held that Eli Lilly's patent claims covering "pemetrexed disodium" would be infringed by Actavis' products containing various alternative forms of pemetrexed, which did not fall within the wording of the claims, properly interpreted, but were nonetheless technically equivalent.


Pemetrexed is a cancer treatment which Lilly has sold under the brand name Alimta since 2004. Lilly has a patent which claims, effectively, the use of pemetrexed disodium in combination cancer therapy.

In order to avoid infringing this patent, Actavis intended to launch products containing a number of alternative forms of pemetrexed, for use in combination cancer therapy: pemetrexed diacid, pemetrexed ditromethamine, or pemetrexed dipotassium. Actavis accepted that these alternative forms are all therapeutically equivalent to pemetrexed disodium, and the judgment considers whether these alternative forms infringe, either directly or indirectly, a claim to use of pemetrexed disodium.

Direct infringement

Lilly argued that, although the words of the patent claim refer specifically to pemetrexed disodium, the claim should be interpreted broadly to cover the alternative but technically equivalent forms of pemetrexed that Actavis proposed to sell. This argument raises an issue with which the Supreme Court is very familiar: how to strike the right balance between giving effect to the specific words used in a legal document, and reaching a conclusion that makes practical sense.

As we discussed in a 2016 article1, this issue arises in relation to a wide range of legal documents - from negotiated contracts to unilateral documents like wills. In the context of patents, the approach to construction is shaped by two unique factors: an express requirement in European patent law to balance literalism and fair protection, and the possibility of using the patent prosecution history to shed light on the "negotiations" between the patentee and the patent office.

Balancing literalism and fair protection

European patent law2 requires a court construing a patent claim to conduct a balancing act between literalism and fair protection, and in particular to take due account of "any element which is equivalent to an element specified in the claims".

Many European jurisdictions apply a "doctrine of equivalents" under which a patent can be infringed by something which is technically equivalent to, but falls outside the wording of, the patent claim. This broader approach had historically been rejected by the English courts: the House of Lords (the predecessor to the Supreme Court as the UK's highest appellate court) held in Kirin Amgen [2005] RPC 9 that the "doctrine of equivalents" extends protection beyond the scope of the claims and is therefore impermissible. The English approach was to treat the wording of the claims as decisive, and to take the existence of equivalents into account merely as part of the background context in order to construe, purposively, the wording of those claims.

The Supreme Court in Actavis v Lilly held that this approach was wrong as a matter of principle, because it approached patent infringement on the basis that there is only one question: whether the alleged infringement falls within the words of the claim. It held that, in order to give fair protection to the patentee, the court must also consider whether something which does not fall within the wording of the claim "on any sensible reading" nevertheless infringes because it is an immaterial variant (or "equivalent").

To implement this new approach the Supreme Court set out a reformulated test for determining the scope of protection of a patent. The Supreme Court held that the court must first determine the "normal" interpretation of the claims, following the established principles of construction considered by the Supreme Court earlier this year (in the context of a contract) in Wood v Capita Insurance Services Ltd [2017] 2 WLR 1095. In the case of a variant which does not fall within the claims as interpreted, the court must then go on to consider whether the variant nevertheless infringes because it varies from the invention in a way which is immaterial.

The test for determination of this second issue is based on the "Improver" / "Protocol" questions developed in previous case law, but with some reformulations and a reduced emphasis on the wording of the claims. The reformulated questions are:

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, i.e. 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 has lowered the hurdle for the patentee to establish infringement in two respects. First, when considering the second question, the skilled person is told that the variant does actually achieve the same result as the invention - previously, the patentee was required to prove that this would have been obvious to the skilled person at the priority date of the patent. Second, the Supreme Court held that when answering the third question, the court should avoid placing too much weight on the words of the claim: "the fact that the language of the claim does not on any sensible reading cover the variant is certainly not enough to justify holding that the patentee does not satisfy the third question".To place too much weight on the words of the claim would result in the second issue —whether an "equivalent" infringes—being effectively decided by the court's determination of the "normal" interpretation of the claim.

Use of the patent prosecution history

The role of the prosecution history —the "negotiation" between the patentee and the patent office during the examination of the patent application—in interpreting patent claims varies in different jurisdictions. The US has a doctrine of "file wrapper estoppel" which requires reference to the prosecution history. By contrast, many European jurisdictions permit reference to the prosecution history only in limited circumstances.

In Actavis v Lilly the Supreme Court confirmed, in line with existing English case law, that the prosecution history is admissible in principle when considering the interpretation of a patent claim, but that it should be treated with scepticism. In this particular case, reviewing the prosecution history did not alter the Supreme Court's initial view that the "equivalents" test was satisfied in relation to Actavis' products.

Direct infringement in France, Italy and Spain

In addition to its UK action, Actavis sought declarations of non-infringement in France, Italy and Spain. The English court's jurisdiction to make those extra-territorial declarations was confirmed by the Court of Appeal in an earlier decision in the same case ([2013] EWCA Civ 517).

At first instance, Arnold J held that the patents were not directly infringed under French, Spanish or Italian law. The Court of Appeal declined to rule formally, but recorded its agreement with Arnold J. In line with its broader approach under English law the Supreme Court disagreed, finding that Lilly's patent was directly infringed in all three foreign jurisdictions.

Indirect infringement

Section 60(2) of the English Patents Act 1977 provides that a patent will be indirectly infringed if

"a person … supplies or offers to supply … any of the means, relating to an essential element of the invention, for putting the invention into effect when he knows, or it is obvious to a reasonable person in the circumstances, that those means are suitable for putting, and are intended to put, the invention into effect"

Actavis' proposed products were to be reconstituted or diluted with a saline solution, and the resulting solution would contain sodium ions and pemetrexed ions in a ratio of at least 2:1. The relevant claim of Lilly's patent was to the use of pemetrexed disodium in the manufacture of a medicament for combination cancer therapy.

The High Court and Court of Appeal had been divided on this issue. Arnold J held that there was no indirect infringement: the claim required the use of pemetrexed disodium in the manufacture of a medicament, and at no stage was pemetrexed disodium used. The Court of Appeal disagreed, holding that Arnold J's conclusion was based on the incorrect conclusion that "pemetrexed disodium" meant "solid pemetrexed disodium". In the view of the Court of Appeal the claim, properly interpreted, also covered a solution including both pemetrexed and sodium ions, the invention was put into effect when a pharmacist or doctor prepared such a solution, and the Actavis products were therefore means relating to an essential element of that invention.

Perhaps unsurprisingly, the Supreme Court agreed with the Court of Appeal's broader interpretation, finding that Actavis' products would also indirectly infringe if Actavis knew, or it was obvious in the circumstances, that ultimate users would dilute those products with saline.


The Supreme Court's decision represents a significant departure from the established English case law in this area. It marks both a more patentee-friendly approach, and an increased desire to ensure harmonisation with the approach taken elsewhere in Europe.

The Supreme Court's decision to depart from the literal meaning of the words used in a patent claim could be viewed as a contrast to the approach it has taken in recent cases relating to contractual interpretation, where the Supreme Court has (in Wood v Capita and Arnold v Britton [2015] AC 1619) rejected attempts to depart far from the plain wording of a contract. In the view of the Supreme Court this results from the distinction between (1) the meaning of the words in a patent claim, which is to be determined following the principles of construction common to all legal documents, and (2) the scope of protection of the patent, which is subject to an express requirement to ensure fair protection for the patentee which is unique to the law of patents.

© 2017 Arnold & Porter Kaye Scholer LLP. This Advisory is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.

  1. Osgerby, K., & Stothers, C. (2017). Contracts, patents and chess—applying Arnold v Britton to patent claim construction. Journal of Intellectual Property Law & Practice, 12(1), 23-29.

  2. Article 69 of the European Patent Convention and the Protocol thereto.

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