Supreme Court considers the role of plausibility in UK patent law

This week the Supreme Court is hearing an appeal in Warner-Lambert v Generics (UK) Ltd (Mylan) and others (UKSC 2016/0197) which will consider the following questions relating to the role of plausibility in UK patent law:

  • “Whether (and what) role plausibility should play in the statutory test for sufficiency, and 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.”
  • “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 gap.”

“Plausibility” has been an increasingly hot topic in patent litigation in recent years, particularly in cases relating to pharmaceuticals, and its rise has not been without controversy amongst patent lawyers.  It has most frequently been associated with inventive step and insufficiency, but it has also come up in relation to industrial applicability, priority and novelty and it is now a firmly established concept for any lawyer considering the validity of a patent.

What is required for something to be “made plausible” has been considered by the Supreme Court before (HGS v Lilly (2011), in which it was found to be a low, threshold test) but that was in the context of industrial applicability.  This appeal to the Supreme Court asks the fundamental question of whether (and what) role plausibility should play in the statutory test for sufficiency.  The Court of Appeal has accepted that plausibility plays a role in sufficiency (and inventive step), based on EPO Technical Board of Appeal case law relating to both inventive step and insufficiency, combining it with English law relating to principles of general application.  It will be particularly interesting to see how the Supreme Court approaches this question, given the firmly established case law in the EPO on this issue.

Fundamentally, this is a question about what is required of a patentee at the time they file a patent application – is it enough for them to speculate in the specification on a possible use for the claimed compounds, in the hope that that speculation will later turn out in fact to be true (if it is not, the claim will be insufficient anyway), or should public policy require that the patentee at least provides some real reason for believing that the proposed use is true at the time of filing, to prevent patentees from excluding others from large areas of research in the hope that active compounds turn up one day?  The answer to that question has potentially significant ramifications for patentees, both in terms of what they need to be including in future patent applications by way of reasoning and/or data (which may affect the stage of the R&D process at which they are able to file them) and in considering the validity of their existing patents.  It is interesting that the UK BioIndustry Association has intervened in the case – more details on their position can be found here.

It’s worth noting that as well as the plausibility questions being considered, the Supreme Court will also hear argument on questions regarding expert evidence on claim construction and abuse of process in relation to late claim amendments, the answers to which may have effects on routine practice in the Patents Court.


Andrew Wells
Andrew Wells
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