16 November 2018

Plausibility – UK’s Supreme Court – New guidance on sufficiency, Swiss-form claims & skinny labels

The Supreme Court has handed down judgement in Warner-Lambert Company LLC v Generics & another [2018] UKSC 56 concerning the validity and infringement of second medical use claims.

This important judgment looks at how plausibility applies to the assessment of the sufficiency of disclosure of second medical use claims, and the test to be used when considering infringement of such claims. The decision may be disappointing news though for patentees but the split decision suggests there is more debate to be had on the topic.


Pfizer’s subsidiary, Warner Lambert, originally obtained a patent for pregabalin (brand name Lyrica) for the treatment of epilepsy and generalised anxiety disorder (GAD).  Warner Lambert then sought patent protection for use of pregabalin to treat pain: Inflammatory, and peripheral and central neuropathic pain.  The patent contains Swiss-type purpose limited process claims, i.e. in the form “use of substance X in the manufacture of a medicament for the treatment of condition Y”.  Claim 1 was for pain in general, whilst subsidiary claims related to the treatment of inflammatory and neuropathic pain.

Following expiry of the compound patent, generic companies sought to market pregabalin for the expired indications of epilepsy and GAD, with Actavis selling its product Leceant under a so-called ‘skinny label.’   However, the problem for Warner Lambert was that generic pregabalin was also being prescribed by doctors for the treatment of pain, despite the patented indication being ‘carved out’ of the generic marketing authorisation and ‘Summary of Product Characteristics.’

The decisions of the lower courts

Actavis and Mylan sought to revoke the patent and Warner Lambert counterclaimed for infringement.  At first instance, Mr. Justice Arnold held that the disclosure in the patent did not make it plausible that pregabalin would treat all types of pain and that only the treatment of inflammatory and peripheral neuropathic pain was sufficiently disclosed.  Therefore, the patent was found to be invalid and Mr. Justice Arnold also refused Warner Lambert’s application to narrow the patent’s claims as an abuse of process.

Upon appeal, Lord Justice Floyd giving the leading judgment in the Court of Appeal upheld the finding of the lower court on insufficiency and also agreed with Mr. Justice Arnold’s decision to reject the application to amend the patent.

In a series of interim decisions, the High Court and the Court of Appeal disagreed upon the approach to be taken to the infringement of second medical use claims in the event that the patent had been found valid.  Mr. Justice Arnold stated in an interim decision that a finding of infringement would require the manufacturer to subjectively intend their product to be used for the protected indications.  However, in the Court of Appeal, Lord Justice Floyd stated that infringement required the manufacturer to foresee that some of their product would be prescribed for the patented indications, unless they had taken all reasonable steps to prevent this from occurring.

The Supreme Court’s decision

The Justices dismissed all of Warner Lambert’s appeals and found that even if the patent had been found valid, it would not be infringed, uphelding the findings of the lower courts that the patent did not make it plausible that pregabalin would treat all types of pain: Only the claim to inflammatory pain was made plausible and sufficiently disclosed.  In a further blow to Warner Lambert, the Justices upheld the cross-appeal of Actavis and Mylan that the claim for the treatment of peripheral neuropathic pain was also insufficiently disclosed, as the rat model data in the patent related only to inflammatory pain.

The decision has confirmed the role plausibility plays in deciding if claims to second medical uses are sufficiently disclosed.  However, the Justices disagreed on the required threshold of disclosure.  A majority of Justices led by Lord Sumption held that the specification must contain more than just an assertion or mere possibility: There must be disclosure of scientific evidence or other reasoning to support the claim to the new medical use.  However, both Lord Hodge and Lord Mance considered that this imposed too high a threshold.

So the issue of plausibility saw their Lordships split in opinion.  Whilst the majority favoured conclusion that the issue of plausibility is just an aspect of the underlying principle of sufficiency: That a patent monopoly must be justified by the technical contribution to the art, it was not without dissent. The key point to take away is that ‘the specification must disclose some reason for supposing that the implied assertion of efficacy in the claim is true’ and, whilst the common general knowledge may be useful in interpreting the teaching of a patent, there must be a disclosure in the patent. This disclosure cannot be merely that something is worth trying. However, for second medical use claims the disclosure may amount to reasonable scientific grounds for the skilled person to expect (believe they could try) there were reasonable prospects of the invention working.

Lords Hodge and Mance dissented; and were more persuaded by the EPO authorities, which they considered were clear that the standard of proof required for plausibility was lower and satisfied if there was a claim which ‘appears scientifically possible, even though it cannot be said to be even prima facie established, without for example testing or assays.’ Their Lordships thought that ‘only if the person skilled in the art would have significant doubts about the workability of the invention’ from the disclosure in the patent would the patent be then implausible.

The Supreme Court also considered the issue of infringement by Actavis’ product if the claims had been found valid in the alternative.  Although the Supreme Court held that the patent would not have been infringed, the Justices differed in their reasoning why.  Both Lord Sumption and Lord Reed considered that the intention of the alleged infringer was irrelevant.  Instead they preferred an ‘outward presentation test;’ i.e. how the manufactured product (including any packaging and labelling) is presented and positioned as being suitable for the patented indications.  Lord Mance went further still and stated that there may be specific circumstances when considering the outward presentation may not be sufficient, and that the generic manufacturer should have been expected to have gone further in his efforts.

Finally, Lord Briggs and Lord Hodge aligned with the view expressed by Mr. Justice Arnold at first instance that the subjective intention of the generic manufacturer is determinative.  Irrespective of the approach taken, all of the Justices decided that the patent would not have been infringed if it had been valid.


The Supreme Court’s decision has major implications for the innovative pharmaceutical industry looking to find new therapeutic uses for existing products.  This is the first time that the Supreme Court has considered the role played by plausibility in the assessment of sufficiency of second medical use claims.  Although plausibility does not appear in the Patents Act, the Supreme Court’s decision confirms that the threshold is low. However, further applications of this decision by the courts will be required before a clearer understanding across a range of circumstances begins to emerge.

In recent years, as high-throughput screening has arguably resulted in the identification of ever fewer new chemical entities (NCE’s), pharmaceutical companies are increasingly looking to find new therapeutic uses for their existing molecules.  However, such research & development endeavours come with a hefty price tag.  Arguably, the Supreme Court’s decision has raised the burden on innovative pharmaceutical companies in proving the sufficiency of second medical use claims.

One final thought comes from the Court’s obiter comments that if an objective approach is taken to direct infringement by the sale of the product of the infringing process (under section 60(1)(c) of the Patents Act 1977), then ‘skinny labels’ carving out the patented indication will often be effective in avoiding infringement.

The full decision from the Supreme Court can be read here.

[1] The Summary of Product Characteristics (SmPC), requires medicine packaging/ leaflets to be approved by the relevant regulator. This includes information on indications and dosages.  There is a requirement that when a generic medicine is authorised that the same information will appear in the ‘product information’ of the generic medicine as that of the reference medicine. However, when patent protection for a reference medicine expires, it is common for further indications of the medicine to remain independently patented.  Thus, the medicine itself can be manufactured without patent infringement but cannot be used for the patented uses. If generics were obliged to include the new indication in their product information they would be liable for patent infringement. Consequently, the European medicines legislation allows the generic applicant for a marketing authorisation to exclude from the product information parts of the labelling referring to indications or dosage forms which are protected by patents. This is often referred to as ‘skinny labelling.’.