On 14 November 2018 the UK Supreme Court (SC) handed down its decision in Warner-Lambert Company LLC v Generics (UK) Ltd t/a Mylan and Actavis, which includes a majority judgment and interesting dissenting ones.

The key claims were held to be invalid for lack of sufficiency, confirming the role of ‘plausibility’ in the assessment of sufficiency, although there was disagreement over how high the plausibility threshold should be.

The SC also indicated that if valid, these claims would not have been infringed, but could not agree unanimously on the correct test for infringement of Swiss-type second medical use claims.

Background to the Appeal

Warner-Lambert had a second medical use patent, EP0934061, directed to the medical use of pregabalin for the treatment of pain (claim 1), inflammatory pain (claim 2) and neuropathic pain (claim 3). The claims are in the old Swiss-type medical use format. An earlier patent directed to pregabalin has expired.

Pregabalin is authorised for the treatment of peripheral and central neuropathic pain, epilepsy and generalised anxiety disorder and Warner-Lambert markets the drug under the brand name Lyrica.

Several generics companies, referred to herein collectively as ‘Actavis’, launched the drug under a ‘skinny label’ for the off-patent indications epilepsy and generalised anxiety disorder. However, Warner-Lambert sought to assert EP0934061, alleging that the skinny label would not prevent infringing uses of the drug. In return, Actavis sought revocation of the patent for lack of inventive step and sufficiency. An intricate legal battle ensued (1).

The first instance court rejected the arguments based on lack of inventive step and these were not at issue before the SC. Instead, validity turned on the issue of sufficiency.

Claim 1 was construed as extending to all pain and Claim 3 as extending to all neuropathic pain. These claims failed for insufficiency because the first instance court held that whilst there was sufficient disclosure in the specification to support the claim that pregabalin was efficacious in the treatment of inflammatory and peripheral neuropathic pain, this was not the case for central neuropathic pain. An application to amend claim 3 to limit it peripheral neuropathic pain was rejected as an abuse of process. These findings were upheld on Appeal.

With regard to infringement, the judges proposed different approaches as to how infringement of Swiss-type claims should be assessed.

The trial judge applied a test of “subjective intent”, namely that the manufacturer must make the product with the intention of targeting the patent-protected market. In contrast, the Court of Appeal applied a test of “objective intent”, which asks whether the alleged infringer knew or could foresee that at least some of the prescriptions for the claimed drug for the claimed indication would in fact be fulfilled with the generic drug. The absence of the claimed indication from the ‘skinny’ label could not “conceivably be sufficient to negative the intention”. Instead, the test will be negative where the manufacturer has “taken all reasonable steps within his power to prevent the consequences occurring”.

Thus, the SC had to consider the following key issues: (i) the construction of the claims, amendment and abuse of process; (ii) the sufficiency of the disclosure in the specification; and (iii) ; and the test for infringement of a Swiss-style medical use patent claim.

The Supreme Court judgement

Construction, amendment and abuse of process

The SC unanimously affirms that claim 1 extends to all pain and claim 3 to all neuropathic pain, whether peripheral or central.

Warner-Lambert’s application to limit claim 3 to peripheral neuropathic pain is rejected as an abuse of process.


There has been significant debate over whether the non-statutory ‘plausibility’ test should play a role in the assessment of sufficiency.

The SC judgment confirms that plausibility is a threshold test that must be used to assess whether a second medical use claim meets the requirement of sufficiency.

The claims at issue were found to be insufficient in relation to neuropathic pain.

Interestingly, the SC judges could not reach agreement on the correct standard for plausibility. The dissenting judges propose a very low standard of plausibility, but the majority’s approach requires the patentee to demonstrate that the specification discloses some scientific reason why the implied assertion of efficacy in the patent claim may well be true [36-37].


The SC judges agree that if claims 1 and 3 had been valid, they would not have been infringed by Actavis, but they differ substantially in their reasons for arriving at this result.

Lord Sumption and Lord Reed consider that the intention of the alleged infringer, whether subjective or objective, is irrelevant. Thus, they propose the “outward presentation” test, under which the sole criterion of infringement is whether the product as it emerges from the manufacturing process, including any labelling or accompanying leaflet, is presented as suitable for the uses which enjoy patent protection [71-86].

Lord Mance agrees that the test depends on the objective appearance and characteristics of the product as it is prepared, presented and put on the market, but considers that in rare cases the context may make it obvious that these are not to be taken at face value [218-223].

Lord Briggs and Lord Hodge consider that the test should be whether the alleged infringer subjectively intended to target the patent-protected market.


Given that the claims at issue were held to be invalid, the SC’s opinions on infringement are orbiter and thus non-binding. We will therefore have to await future judgments to receive binding guidance on the issue of infringement of Swiss-style medical use claims.

It is also worth bearing in mind that the Warner-Lambert claims were in the Swiss-style format, i.e. they were purpose-limited process claims. Second medical use inventions must now be claimed in Europe in the form of purpose-limited product claims (the ‘EPC2000’ format). The test for infringement of purpose-limited product claims will necessarily differ.

It is clear that to avoid infringement of a Swiss-style claim in the UK, a generic product should not identify in its packaging, labelling or patient instruction leaflet any potential uses which are subject to patent protection. However, this alone may not necessarily guarantee a finding of non-infringement in the UK. Of course, it must also be borne in mind that there is no harmonised approach to the assessment of infringement throughout Europe.


(1) See our earlier post here and references therein

“These proceedings raise, for the first time in the courts of the United Kingdom, the question how the concepts of sufficiency and infringement are to be applied to a patent relating to a specified medical use of a known pharmaceutical compound.”