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UK – Supreme Court / Warner-Lambert v. Mylan & Actavis / second medical use / plausibility

14 Nov 2018

The UKSC has introduced a new test for the infringement of Swiss form second medical use claims and clarified the application of the test for plausibility of purpose-limited claims, by Tim Powell, Bethan Hopewell, Siddharth Kusumakar and Joel Coles, Powell Gilbert LLP 

The United Kingdom Supreme Court (UKSC) today handed down its highly-anticipated judgment in the case of Warner-Lambert v Mylan & Actavis ([2018] UKSC 56)


Warner-Lambert was the proprietor of a patent that claimed the use of pregabalin (marketed as Lyrica) in the manufacture of a medicament for use in treatment of pain and, in particular, to neuropathic pain and various sub-categories of peripheral neuropathic pain.

Actavis and Mylan sought to revoke the patent on the basis that the disclosure in the specification did not render the claims to the treatment of neuropathic pain conditions plausible and hence the claim to the treatment of pain as plausible across its scope. Warner-Lambert commenced infringement proceedings in relation to Actavis’s “skinny label” pregabalin product (marketed as Lecaent), which was authorised and marketed only for the non-patented indications of epilepsy and generalised anxiety disorder.

At first instance, the High Court held that the claims to the treatment of pain and neuropathic pain were invalid on the ground of insufficiency as they were not rendered plausible across their scope. However, despite the patent containing no data from an animal model of neuropathic pain, the High Court held that the claims to sub-categories of peripheral neuropathic pain were plausible.

The High Court further held that, even had they been valid, Actavis’s “skinny label” product would not have infringed the asserted claims. The High Court also held that an attempt by Warner-Lambert to make a post-trial amendment to limit the neuropathic pain claim to peripheral neuropathic pain was an abuse of process.

The Court of Appeal upheld the High Court’s decision on validity but provided obiter guidance on the test for infringement, holding that it is only essential that the manufacturer is able to foresee that there will be intentional use for the patented indication but that a manufacturer would avoid infringement where all reasonable steps within his power had been taken to avoid use of the drug for the patented indication. The Court of Appeal also rejected Warner-Lambert’s application to amend the patent post-trial as an abuse of process.

Supreme Court Judgment


The UKSC concluded (by a majority) that the correct test for direct infringement of Swiss form second medical use claims is the “outward presentation” test, in which the objective characteristics of the manufactured product are to be considered rather than the intention of the manufacturer. (The minority of the court adopted Actavis’s position that the correct test should be one of subjective intention on the part of the manufacturer, rather than the foreseeability test favoured by Warner-Lambert).

The “outward presentation” test had not been advanced by the parties or the interveners, but was addressed in written submissions after the hearing at the invitation of the court. Whilst the UKSC recognises that the outward presentation test may confer imperfect protection in respect of Swiss form second medical use claims, it was held that such imperfect protection arises from a limitation inherent in a Swiss-form patent.

The UKSC also rejected Warner-Lambert’s claim for indirect infringement on the basis that the invention protected by Swiss form claims is the manufacture of the drug for the designated use, and not the subsequent use of the product for treating patients (including, for example, affixing a sticker to the product by the pharmacist).


The UKSC confirmed that the claims to the treatment of pain and neuropathic pain were invalid as these claims were not plausible across their scope on the basis of the disclosure in the patent. However, the majority also agreed with Actavis that the dependent claims to sub-categories of peripheral neuropathic pain were also invalid for lack of plausibility on the basis that, whilst the patent contained data relating to inflammatory pain, it lacked any data showing that the drug would be efficacious for any neuropathic pain condition.

In applying the reasoning of the Technical Boards of Appeal of the European Patent Office (in particular the decision in Salk Institute for Biological Studies/AP-I complex (T 609/02)), the UKSC held that it is always necessary for the patentee to demonstrate in the specification something that makes the claim to therapeutic efficacy plausible and that a mere assertion of efficacy is not enough. Furthermore, the patentee cannot claim a monopoly of a new use for an existing compound unless it not only makes but discloses a contribution to the art and therefore it must be possible to derive from the teaching of the patent some reason for supposing that the implied assertion of efficacy in the claim is true.

The UKSC held that whilst post-filing data may be admissible in a dispute about sufficiency, the purpose for which they are admitted is strictly limited either to confirm the plausibility of the therapeutic use or to refute a challenger’s contention that it does not actually work. Post-filing data cannot, however, be used as a substitute for sufficient disclosure in the specification.

Claim amendments / abuse of process

Finally, the UKSC confirmed that Warner-Lambert’s attempt to amend its patent post-trial amounted to an abuse of process. In so doing, the UKSC drew a distinction between post-trial amendments to delete claims which had been found to be invalid at trial and post-trial amendments designed to set up a new claim which had not been adjudicated upon at trial.


In extensive obiter remarks on infringement of Swiss-form patent claims, the UKSC has provided important guidance on what, as a matter of construction, it means to claim in a patent the use of compound ‘X’ for the preparation of a medicament “for” treating disease ‘Y’.

By rejecting the importation of a mental element into the claim and opting for a test of purpose based upon the “outward presentation” of the manufactured product, the UKSC has sought to take account of the Protocol on the interpretation of Article 69 EPC (i.e. affording reasonable protection to the patentee and the need for legal certainty for third parties) and broader policy objectives including the public interest in the free exploitation of a product for a patent-expired use.

The outward presentation test provides generic manufacturers with a clear framework for launching into second medical use markets that also aims to safeguard from liability other third parties who deal in such generic products (e.g. distributors and dispensing pharmacists).

Whilst this is a landmark judgment, it likely marks only the beginning of a new chapter. The challenges raised by the scope of protection of second medical use patents are abundantly apparent from the lengthy considerations of several of the Justices.

In particular, the UKSC acknowledges the difficulties of ‘extreme’ cases where the outward presentation test may afford insufficient protection to the patentee (e.g. where a generic manufacturer encourages dealers and pharmacists to supply a product for the treatment of a patented indication despite its outward presentation being directed to the non-patented use only).

The UKSC leaves open the position in this type of ‘remote situation’ and recognises the potential need for the legislature to address the practical issues that may arise from purpose-limited patent protection. This is a reminder that generic manufacturers should still act responsibly.

The UKSC has also confirmed the place of plausibility as part of the sufficiency test for second medical use claims. In light of the judgment, patentees should ensure that patent specifications contain sufficient data not only to ensure that each claimed therapeutic use is supported but that they are supported across their scope. Claims should therefore be suitably drafted to ensure that only those therapeutic uses which are supported are covered in order to minimise the risks that such claims are held to be invalid for lack of plausibility.

The UKSC’s decision upholding the lower court’s findings on abuse is a reminder to litigators to consider all of the options available to them during the course of proceedings, and to take timely action where necessary. In the case of “scope of claim” arguments, in particular, patentees should avoid relying on construction arguments alone, where an allowable amendment may otherwise rescue the claim.

The judgment can be accessed here.
The UKSC’s press summary can be accessed here.

Actavis was represented in these proceedings by Powell Gilbert LLP