UK: Warner-Lambert V Mylan: Supreme Court Rules On Plausibility And Infringement Of Second Medical Use Claims

Last Updated: 18 December 2018
Article by Will Jensen

The Supreme Court has handed down its long-awaited decision in Warner-Lambert Company LLC (Appellant) v Generics (UK) Ltd t/a Mylan and another [2018] UKSC 56. It is the culmination of the nearly four year dispute between Warner-Lambert (part of the Pfizer group of companies), Mylan and Actavis in relation to the validity  and infringement of Warner-Lambert’s patent EP(UK) 0 934 061 and Actavis’ LECAENT product. The decision has been hotly anticipated as it was expected to rule on two key issues: the sufficiency  requirements of second medical use claims and the correct test for infringement of such claims in the Swiss form.


The litigation concerned Warner-Lambert’s prescription-only drug pregabalin, which it markets under the trade name LYRICA and which is prescribed to treat epilepsy, generalised anxiety disorder and neuropathic pain. Warner-Lambert’s patent covering pregabalin itself has expired, but it has a second medical use patent for the use of pregabalin for the preparation of a pharmaceutical composition for treating pain. Actavis had applied for authorisation to market its pregabalin LECAENT under a skinny label, which would restrict its use to treating epilepsy and general anxiety disorders. Warner-Lambert brought an action against Actavis for direct and indirect infringement of its patent arguing that the skinny label would not prevent the cheaper Actavis product being dispensed for the treatment of pain.

The litigation has focussed on claims 1 to 3 of the patent. These are written in the Swiss form and claim the use of pregabalin for the treatment of pain, and (dependent on claim 1) its use for inflammatory pain and neuropathic pain.

At first instance, Arnold J found the patent inventive but insufficient and rejected an application after judgment to narrow the claims as an abuse of process.

The Court of Appeal upheld the judge’s findings (with some exceptions not relevant to the Supreme Court’s findings).

Infringement therefore did not arise, although Arnold J found that if claims 1 and 3 had been valid, they would not have been infringed. The Court of Appeal held that Arnold J had applied the wrong test but declined to decide on the point in the absence of the findings of fact on their preferred test.

The Supreme Court heard appeals in relation to: 

  1. The construction of the claims, and in particular Claim 3 (neuropathic pain).
  2. The sufficiency of the disclosure in the specification.
  3. Amendment and abuse of process.
  4. The test for infringement of a Swiss form claim.

It is fair to say that it was issues (2) and (4) that were the most hotly-anticipated.  

Construction of claims 1-3 and the application to amend

In relation to issues (1) and (3), the Supreme Court upheld the lower courts’ decisions: Claim 1 extends to all pain and Claim 3 to all neuropathic pain, whether peripheral or central; and, the post-judgment application to narrow the claims was an abuse of process.

Sufficiency of the disclosure and plausibility

In relation to the sufficiency of disclosure of the specification, the Supreme Court looked closely at the support in the specification for the types of pain claimed. It found that the disclosure in the specification supported the claims in relation to inflammatory pain, but not neuropathic pain, whether peripheral or central. Claims 1 and 3 were found invalid for insufficiency.

In relation to the test of whether the claims were plausible (and hence sufficient), the Supreme Court (by a majority) found that the test adopted by the Court of Appeal in the case was too easy. Lord Sumption stated: “The test is relatively undemanding. But it cannot be deprived of all meaning or reduced, as Floyd LJ’s statement does, to little more than a test of good faith. Indeed, if the threshold were as low as he suggests, it would be unlikely to serve even the limited purpose that he assigns to it of barring speculative or armchair claims.

Lord Sumption went on at paragraph 37 to make some useful points on plausibility in the context of the present case. His 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. More than a bare assertion or mere possibility of therapeutic efficiency is required, though a priori reasoning (not necessarily only experimental data) may suffice. This respects the principle that the patentee cannot claim a monopoly of new use for an existing compound without real disclosure.

Lord Hodge and Lord Mance disagreed and preferred a lower standard of plausibility.

Infringement of Swiss-form claims

Finally, in relation to the test for infringement of a patent in the Swiss form, the court looked at infringement under both s.60(1)(c) and s.60(2). The court unanimously held that had claims 1 and 3 been valid, they would not have been infringed under s.60(1)(c) or s.60(2). In relation to s.60(1)(c), the Lordships’ reasons for arriving at this conclusion were very different:

Lord Sumption and Lord Reed preferred an “outward presentation” test: “the intention of the alleged infringer is irrelevant and that 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.” In this case it was not: “LECAENT was sold with patient information leaflets to the effect that it was for the treatment of seizure disorders and GAD.

Lord Mance agreed that “the test depends on the objective appearance and characteristics of the product as it is prepared, presented and put on the market, but leaves open the possibility (i) that in rare cases the context may make it obvious that these are not to be taken at face value, and (ii) that there may be circumstances in which the generic manufacturer should positively exclude use for the patent-protected purpose.” Lord Mance gave several examples of the context or circumstances where such a finding of infringement may be found, a powerful one being where a generic manufacturer produced and supplied “quantities of the pharmaceutical composition for a distributor in a context which only made sense if they were destined for the patent-protected use”.

Lord Hodge and Lord Briggs preferred the view of Arnold J: “the test is whether the alleged infringer subjectively intended to target the patent-protected market.” Arnold J had found that they did not.

With the infringement question still open, it will be interesting to see how courts will treat Swiss form claims in the future. Lord Briggs commented that although “Swiss-form claims are now a closed class (because they have been replaced for the future by purpose-limited product claims under article 54(5) of the EPC 2000) there are sufficient still in force for the issues as to infringement to have potentially wide-ranging consequences.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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