Implausibly incredible or just plain insufficient?

Warner-Lambert is a subsidiary of pharma giant Pfizer and it has a patent for a drug called pregabalin, sold under the trade mark Lyrica. The patent was the subject of a decision of Mr Justice Arnold [2015] EWHC 2548 (Pat), which the Kats pawed over here. His decision was upheld by the Court of Appeal in Warner-Lambert v. Actavis and Generics [2016] EWCA Civ 1006, unravelled by the Kats here

The case touched on a number of issues, both substantive and procedural, but the one of most interest to this GuestKat is the decision on insufficiency, based on which several claims of the patent were held invalid. As a result, Pfizer will not have patent protection for Lyrica in respect of its use as a treatment for certain types of pain, because it was found that there was no basis for saying that it was "plausible" that pregabalin would be effective for all types of pain. Against that background, the patentees have appealed to the UK Supreme Court, which has agreed to hear the case. The main issue before the Supreme Court is whether “plausibility” should play a role in the statutory test for sufficiency of disclosure. 

This GuestKat has had his claws in patent law for a long time, but does not remember reading the word “plausible” in the EPC or the Patents Act 1977.  So where has it come from? The Court of Appeal judgment refers back to Regeneron v. Genentech [2013] EWCA Civ 93 [2013] RPC 28, in which it was said that this requirement originated in the jurisprudence of the Boards of Appeal of the EPO, following from the decision in T 939/92 Agrevo/Triazole herbicides. As Mr Justice Arnold explains in his decision, there are two types of insufficiency according to the case law: “classical insufficiency”, which means failure to enable the invention to be performed without undue burden, and “Biogen  insufficiency” (named after Biogen v Medeva [1997] RPC 1), which is a failure to enable the invention to be performed over the whole scope of the claim.

Lord Justice Kitchin in Regeneron said that it must be possible to make a reasonable prediction that the invention will work with substantially everything falling within the scope of the claim or, "put another way", the assertion that the invention will work across the scope of the claim must be "plausible or credible". Another way of characterising this type of objection is as a matter of “excessive claim breadth”, although this is not an express ground on which a patent can be revoked.

The crux of the matter, looking at it in the context of chemical inventions, is that you can’t just make up a generic formula that covers a wide range of compounds and leave it to the imagination or later investigation to see if some or all of those compounds might be in some way useful.  Lord Justice Floyd in the Court of Appeal in the present case said one could draw the conclusion from the cases that a mere assertion that compound X is suitable for treating disease Y is not sufficient without more to render the invention “plausible”.  

A related issue, looking at things from the point of view of inventive step, is whether something is “obvious to try”. Here, "a reasonable expectation of success" is required, which Mr Justice Henry Carr in Actavis v. Lilly [2015] EWHC 3294 (Pat) ruled should not be equated with "plausibility."  He said the latter is a threshold test, which asks just if the invention is "credible", based on the patent and common general knowledge. This GuestKat thinks a definition in terms of another word - "credible" - doesn't really help here, especially when the two words seem to have been used interchangeably in Regeneron, but the point seems clear that "plausibility" is not to be elevated to the status of an additional criterion for patentability.

A patent can only be found invalid based on specific grounds, and the relevant one here is that the specification does not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art. If such a person can’t tell from the information provided in the patent whether or which parts of the invention will or won’t work, then that requirement is not met and the patent will be invalid. 

This GuestKat wonders whether it is right to introduce additional words and concepts into the assessment of validity, such as “plausibility” and “credible”, which are not to be found in the statute or the convention. The danger is then that they take on a significance of their own. Thus, in this case, the Supreme Court is being asked to address the question "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".  This GuestKat awaits the judgment with interest.
Implausibly incredible or just plain insufficient? Implausibly incredible or just plain insufficient? Reviewed by Stephen on Wednesday, May 31, 2017 Rating: 5


  1. It is just plain insufficient. Surely that is, and should be, the end of the story. But with so much money riding on this, the creative silks will surely have their way with the Supreme Court judges. Then whatever decision they ultimately hand down (good, bad or ugly) will be for everyone else to have to deal with.

  2. I do find it odd that, whereas the UK courts seem to treat decisions of the lower EPO Boards of Appeal as having the same legal precedent authority as decisions of the UK courts, the EPO itself does not.

    There are many references to this scattered throughout published EPO decisions, for example T0910/06

    "...unlike some Anglo-Saxon legal systems which are precedent driven the instances of the European Patent Organisation work within a codified system of law, i.e. the European Patent Convention and its implementing regulations, and are constrained by case law only in the case of decisions handed down by the Enlarged Board of Appeal. Further the ratio descendi of a decision of a Board of Appeal is only binding, in the case of remittal, on the department whose decision was appealed in so far as the facts are the same (Art 111(2) EPC). " [Reasons, 2.8]

  3. Nonsense comment. The patent claimed the use for the treatment of neuropathic pain. The compound is, in fact, suitable for treating neuropathic pain. The patent teaches you to take a tablet of the drug to treat said pain. Seems sufficient to me. What more do you want?

  4. Does this also help us with novelty, for example where a patent publication discloses that a compound is useful for a large number of conditions, including condition (a), but without "plausibility/credibility", and then we claim the compound for treating this condition, with data to back it up?

  5. The ordinary civil burden of proof is - more likely than not. I wonder, is - plausible - no more than a reference to that standard?

  6. Plausibility is important to have as a separate concept from being able to carry out the invention. EPO decision T1329/04 is important here because it shows it needs to be shown in the specification that the molecule in question has the properties needed to solve the problem.

    So plausibility is needed for biotech/pharma case law to continue to function, and it's good for it to develop in the UK as a separate enablement requirement (different from being able to carry out the invention or Biogen insufficiency)

    Given that the EPO is actively using plausibility as a criterion I cannot see how the Supreme Court could decide against it

  7. This also presumably means the infringement test for a skinny label Swiss style claim could change again (and that is all about the plausibility the infringer trying to stop people from carrying out the patented use!)

  8. I find it helpful to think of "plausibility" as an evidential requirement rather than a legal test. The legal requirement is that the skilled person should be able to perform the invention across the full breadth of the claim - ie the skilled person, with the teaching of the patent and his common general knowledge, should be able to make anything falling within the scope of the claims. To perform "the invention", you need the physical thing that falls within the claim but in addition the thing must have the quality that caused the patentee to claim it - the quality(ies) identified for the invention in the patent (that's what I take the AGREVO line of cases to mean). The problem is that, as a matter of evidence, nobody is going to have the time to make and test everything to see whether it has that quality. So we work with a rebuttable presumption that the thing will have the quality if it is plausible, on the basis of what the specification says plus common general knowledge, that it will have that quality. Post-filed evidence can confirm that what is plausible is in fact the case, or the presumption can be rebutted by evidence that the qualities are lacking.

  9. ....and how about Section 1 (1) (c) of the 1977 Act, industrial applicability. Is "plausible" the wrong enquiry?

  10. 'Biogen Insufficiency' seems to this fossil an attempt to re-enact invalidity for lack of fair basis, which ground of revocation disappeared from our law with the repeal of the '49 Act.

  11. That last commenter refers to one of the old invalidity grounds, which disappeared in 1977. Of course, there are many of them.

    But the reasons why a claim ought to be struck down haven't changed. You know, all that "scope commensurate with the contribution" stuff.

    So today, when the courts see an over-wide claim, they are obliged to get creative with the law on insufficiency and inventive step. What else are they supposed to do?

  12. In response to MaxDrei, yes, case law is always fashioned through actual cases, and that keeps it relevant to the new technologies that are emerging, and new tricks developed by patent attorneys. It's important for higher courts to have that freedom to go beyond the literal wording of the legislation whenever they need to.


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