Keta Lomidze and Alasdhair McDonald, who both work within the intellectual property team at CMS, preview the decision awaited in Warner-Lambert Company LLC v Generics (UK) Ltd t/a Mylan & Anor:

A highly publicised dispute, concerning second medical use protection of the drug Pregabalin, has finally reached the Supreme Court and is currently awaiting its decision.


Warner-Lambert is the proprietor of the patent for the prescription-only drug Pregabalin, marketed under a single registered trade mark Lyrica, and has the rights to market the drug for three different indications: epilepsy, generalised anxiety disorder and neuropathic pain. Patent protection for Pregabalin expired in 2013 in relation to epilepsy and anxiety disorder (the “Non-Patented Indications”), but Warner-Lambert still owned second medical use patent, which covered the use of Pregabalin for treating “pain” (claim 1) and for treating pain wherein the pain is neuropathic pain (claim 3) (the “Patented Indications”). A claim for the use of a substance for a particular aim is termed a “Swiss form claim”.

Actavis and Mylan, the manufacturers of generic drugs, sought revocation of the patent on the grounds of insufficiency of disclosure of the specification. Actavis also applied to market generic version of Pregabalin under the Lecaent trade mark, limited to the Non-Patented Indications. Concerned that Lecaent might be used to treat pain, particularly in an environment where pharmacists are encouraged to dispense generic drugs, where available, by way of incentives, Warner-Lambert commenced infringement proceedings against Actavis. It had also sought an interim injunction requiring Actavis to take positive steps to prevent Lecaent being supplied for the Patented Indications.

The High Court denied Warner-Lambert’s application for interim injunction on the basis that there was no serious issue to be tried on infringement. Actavis applied for the entire claim to be struck out or for summary dismissal. Notwithstanding the court’s finding that Lecaent did not come within the ambit of the indication-limited patent, Arnold J refused to strike out the case entirely holding that Swiss form claim is still a “developing area of law” and so a matter suitable for the higher courts.

In relation to the claim for indirect infringement, Warner-Lambert could not prove that Actavis had intended to supply, or offer to supply, Lecaent for the Patented Indications. Arnold J held that for an infringing act to occur, Warner-Lambert had to show that the manufacturer intended to supply the medication for Patented Indications. A mere knowledge and possibility to foresee that the infringing act may occur was held not to be sufficient, thereby not satisfying section 60(2) Patents Act. Warner-Lambert appealed.

The Court of Appeal upheld Arnold J’s decision not to grant interim injunction, but allowed Warner-Lambert’s appeal against the decision to strike out indirect infringement of Swiss form claim. The Court of Appeal disagreed with the High Court’s finding that infringement of Swiss form claim required subjective intent on the part of the manufacturer. The knowledge and foreseeability of the manufacturer that the drug might be used for the Patented Indications was held to be sufficient for the infringing act to occur. The case proceeded to full trial.

Decisions of the High Court

 In a series of decisions, the main issues considered by the court concerned the questions of sufficiency of disclosure, abuse of process and infringement.

Sufficiency of disclosure

The court held that Warner-Lambert failed to establish that some of its claims – claim 1 and claim 3 – were valid on the grounds of sufficiency. Arnold J’s construction of treating “neuropathic pain” (claim 3) extended to both central neuropathic pain and peripheral neuropathic pain. Expert evidence led the judge to conclude that data in the patent and the common general knowledge of those in the field, meant that it would only have seemed plausible to the skilled addressee of the patent that Pregabalin would be effective in treating peripheral neuropathic pain (and not central neuropathic pain). One test for sufficiency in patent claims is whether it is plausible at the priority date that the invention has efficacy across the whole scope of a claim. Warner-Lambert’s claims as regards treating peripheral neuropathic pain were plausible and valid, but it fell short of passing the plausibility test as regards treating central neuropathic pain. Since the claims were only partially valid, and not across their breadth, they were held to be invalid on the whole.

Abuse of process

To counter attacks on grounds of insufficiency, Warner-Lambert sought permission to amend its claims to limit to peripheral neuropathic pain. However, Arnold J held that to allow amendment at post trial would amount to an abuse of process.


Arnold J followed the Court of Appeal’s construction of the Swiss form claims requiring both knowledge (including constructive knowledge) and foreseeability of intent on the manufacturer’s part. He then went on to find that even if the claims were sufficient, infringement would still not be made out under sections 60(1) and 60(2) of the Patents Act.

Intention of the doctor, who is ultimately the person prescribing the drug for the purpose of treating neuropathic pain, and of the pharmacists (albeit to a lesser degree) was held to be relevant considerations in finding infringement. However, most crucially, it is the manufacturer’s intention and foresight of what happens to the drug that plays key role in determining the infringing act.

In the present case it could not be shown that Actavis, either in the period before it took the steps to notify the prescribers for which indications the drug to be supplied or the drug manufactured at a later date, would have foreseen that Lecaent would be intentionally prescribed or dispensed for Patented Indications. Direct infringement under section 60(1) was therefore not made out.

As regards indirect infringement, the court confirmed its interim judgment and held that Swiss form claims are: “claims to processes of manufacturer, but there is no act of manufacturer by any party downstream from Actavis, nor even the prospect of an act …”

Notwithstanding Actavis’ generic drug ingredient is “means relating to an essential element of the invention for putting the invention into effect”, Lacaent was found not to be suitable for putting, or intended to put, the invention into effect. It is either the invention has already been put into effect by the time the drug left Actavis’ hands or it was not put into effect at all, thereby not satisfying section 60(2) Patents Act.

The Court of Appeal’s findings

The Court of Appeal had to decide whether the lower instance finding that: (i) Warner-Lambert’s claims were invalid on the grounds of insufficient disclosure; and (ii) the application to amend the claim 3 by limiting it to exclude “central neuropathic pain” was an abuse of process.

The court sided with Arnold J’s decision and found the patent to be invalid. The lack of data and the experimental model used in the claims were held insufficient and not plausible to treat central neuropathic pain, only peripheral neuropathic pain.

As there was no claim as regards peripheral neuropathic pain, the court upheld High Court’s decision on the facts and decided that to allow Warner-Lambert’s application to amend its claim at post trial would amount to an abuse of process.

Although the patent claims were held to be invalid, the court, obiter, provided some guidance on potential infringement of second medical use claims in Swiss form.

The court commented that assessment of direct infringement in second medical use claims require an objective approach, i.e. what one considers a manufacturer should have known or reasonably foreseen that the drug would be intentionally used to treat the patented indications. Further, the requisite intention will not be present where manufacturer has taken all reasonable steps in his power to prevent the consequences of his actions to occur, albeit carving out alone will not necessarily prevent the infringing act from occurring. Equally, intention of the doctor and the pharmacists (and to some degree the patient) are all relevant considerations in determining the manufacturer’s knowledge and foreseeability as regards intentional use of the drug for new medical indication. The true test to be applied is what the manufacturer could reasonably know or foresee the consequences of his or her action to be.

As regards indirect infringement, the Court of Appeal held that when considering the act of “putting the invention into effect” under section 60(2), it may be necessary to look not just at what any one person in the chain is carrying out the invention. The process of invention may not be completed by subsequent preparation of a pharmaceutical composition. The preparation and packaging act by the manufacturer and a subsequent labelling step performed by a pharmacists can be seen as a continuation of the process.

Issues to be decided by the Supreme Court

Warner-Lambert is now appealing to the Supreme Court to decide on the following issues:

  • whether (and what) role plausibility should play in the statutory test for sufficiency;
  • whether a patent should be held insufficient for lack of plausibility even though it is in fact enabled across the full scope of the claim; and
  • if a plausibility test is appropriate, provided there is basis to support the claim across part of its scope, whether later evidence can be used to fill the gaps; and
  • the correct approach to (and the use of expert evidence in) the construction of patent claims, and whether a post-trial application to amend an invalid patent claim to limit it to a part found to be plausible is an abuse of process.


“Plausibility” attacks in patent law are not enshrined in statute or in the EPC. Rather, plausibility has been read into existing statutory grounds to challenge the validity of the patent, being obviousness and sufficiency.

The current law on plausibility means that patentees, particularly in the pharmaceutical field, have to file their patents in what is often an extremely narrow window of time. In order to establish that a claimed use for a product is plausible, it typically needs to be supported by some empirical data which renders the claimed invention “plausible”. But how extensive these data need to be, and how far they must go to support the claimed invention, is unclear and arguably has varied on a case by case basis.

This places the patentee in a bind: if it files too soon, its patent might be “implausible”, but if it waits too long, the invention might be disclosed or become obvious, or it might be pipped to the post by a competitor. The Supreme Court’s ruling on this point is therefore eagerly awaited.