Supreme Court eases patent pain for the NHS, but leaves confused answers for drug companies: Warner-Lambert v Generics Part 1

The UK Supreme Court’s ruling last week in a long-running patent dispute between Warner-Lambert and Generics UK (discussed here and here) brings welcome clarity, almost, to the questions of infringement of Swiss-form claims, and insufficiency for pharma patents. But in the end it is a missed opportunity given the diverging views of the five judges involved and the absence of clearly stated principles.

Supreme Court decisions on patent law are unusual and very significant.  We will provide a fuller analysis of the implications of this ruling, but for now, here is an overview. We will look at the insufficiency issues in Part 1 of this series, and infringement in Part 2 (Warner-Lambert v Generics Part 2: infringement).


A patent is often explained in terms of a bargain between a state and an inventor. The inventor is given a period of exclusive use or control in exchange for making the invention available to the public.

“The inventor has the benefit during the term, and the public have the benefit after…”

Part of this bargain is giving a full explanation of the invention to a reader. The European Patent Convention and the UK Patents Act require a patent to disclose the invention claimed in a manner which is clear and complete enough for it to be “performed” or “carried out” by a skilled person. Failure to do so means that the patent is invalid.

Looked at simply, this could just mean that the inventor has to give enough information for a reader to perform the invention claimed. But there are some kinds of patent where this simple approach doesn’t work. A more subtle analysis of sufficiency is then required, as explained in an earlier House of Lords decision (Biogen v Medeva):

“It is not whether the claimed invention could deliver the goods, but whether the claims cover other ways in which they might be delivered: ways which owe nothing to the teaching of the patent or any principle which it disclosed.”


“the extent of the monopoly claimed exceeds the technical contribution to the art made by the invention as described in the specification.”

With a second medical use patent, like the one in this dispute, it is entirely possible for a clinician to simply read the patent and then treat a patient with the medicine for the claimed indication (ie for the second medical use). But the patent may not provide any practical evidence or theoretical basis that using the medicine will actually work.  A patent applicant could have listed a series of conditions that the drug might be used for, without having done any supporting research, or could have claimed more broadly than the research warranted.  Of course, one might ask: does this matter if in fact it is subsequently found that the medicine does work for that indication?

Warner-Lambert’s patent included claims for the use of known drug, pregabalin, in the treatment pain generally, and more specifically in the treatment of neuropathic pain. But the disclosure of the patent only gave experimental data for the treatment of inflammatory pain. Should a patent like this be valid?

The Supreme Court looked at earlier case law, both in the UK and at the European Patent Office, and they identified a need for the claimed new use to be plausible. Disagreeing with the Court of Appeal’s conclusions that:

““the threshold was not only low, but that the test could be satisfied by a “prediction … based on the slimmest of evidence” or one based on material which was “manifestly incomplete””

their alternative requirement was

“the specification must disclose some reason for supposing that the implied assertion of efficacy in the claim is true”.

 The information given in the patent all related to treatment of inflammatory pain, and not pain in general. There was no unifying principle that made it plausible that it would also work with neuropathic pain, and so the patent was invalid.

What isn’t clear is how far this analysis will apply outside the sphere of second medical use patents. The statement that the threshold is low should make it more difficult to run an argument that "if the claimed invention is not obvious, then it is insufficient" -- currently featuring in a number of defences to infringement claims. 

However, disagreement between the judges on whether a plausible unifying principle (or experimental basis) must always to be disclosed in the patent, or only where a reader would think the scope of the claimed invention inherently implausible, could open the door to more formalistic objections to sufficiency. Although tempting to run, we doubt that this would be followed, at least outside the realm of second medical use patents.

What’s more, two of the judges preferred a different approach. They felt that the threshold put forward in the majority judgment was too high, leaving open the prospect of future uncertainty in this area.

In Part 2 of this series, we look at the infringement questions. Does a person in the supply chain need to know what is in the mind of the product's manufacturer in order to avoid infringing themselves?

Alasdair Poore and Mark Pearce

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Every piece of content we create is correct on the date it’s published but please don’t rely on it as legal advice. If you’d like to speak to us about your own legal requirements, please contact one of our expert lawyers.

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