Plausibility demystified - a review of EPO case law before G 2/21

The European patent attorney community is currently eagerly awaiting the decision of the Enlarged Board of Appeal referral G 2/21 on the thorny topic of plausibility and post-filed evidence. 

In its preliminary opinion for G 2/21, the Enlarged Board of Appeal (EBA) raised some eyebrows by appearing to reference the standard test for sufficiency (IPKat). The sufficiency test is considered a relatively low bar, whereby an invention is considered sufficiently disclosed in view of the lack of any substantiated doubts that a skilled person could work the invention. Establishing the plausibility of an invention is often considered a higher bar than the standard sufficiency test However, in this Kat's view, the EBA preliminary opinion is aligned with the EPO's normal use of the term plausibility, according to which plausibility is not a higher sufficiency bar. While we wait for G 2/21, it is therefore worth stepping-back and taking a broader look at plausibility and its use in the established case law of the Boards of Appeal. 

The problem of plausibility

There are two reasons why the concept of plausibility can appear so muddled (or in Sir Robin Jacob's words, "Humpty-Dumpty-ish"). First, plausibility is not a legal concept finding explicit basis in the EPC. The EPC requires an invention to be sufficiently disclosed (Article 83 EPC), but does not mention "plausibility". Second, plausibility is employed by the EPO in a number of different contexts, including the sufficiency of medical use inventions and inventions involving broad ranges, as well as in inventive step analysis. 

However, once the rationale behind the plausibility test is understood, in this Kat's view, it becomes clear that there is nothing mysterious or difficult about the concept. Plausibility is simply the way in which the EPO expresses a higher degree of existing doubt about certain types of invention. If there is more underlying doubt that an invention will work, then an applicant must provide more evidence and information about the invention in exchange for the grant of a patent. The need for this additional evidence is the plausibility requirement. 

Basic Sufficiency

In order to understand plausibility, it is first necessary to understand sufficiency. In order to be sufficiently disclosed under Article 83 EPC, a detailed description of at least one way of carrying out the invention must be given in the application. An objection of insufficiency requires there to be serious doubts, substantiated by verifiable facts, that the skilled person would be able to work the invention (II-C, 9). As the recent case T 0500/20 confirmed, the sufficiency bar is usually low, and can be satisfied by providing a single example falling in the scope of the claim in the application as filed. 

Therapeutic use plausibility (Fish medicine, T 1571/19)

Grasping the slippery concept of plausibility
For most inventions there usually are not any serious doubts, substantiated by verifiable facts, that the skilled person would be able to work the invention. For other types of invention, however, there is greater doubt about whether a skilled person would be able to work the invention. For example, there is usually a high level of doubt that a new chemical compound will cure cancer. This is because most chemical compounds don't cure cancer, and some experiments and data are usually needed to establish any level of likelihood that a chemical compound will cure cancer. There is consequently often a high level of underlying doubt that a randomly selected chemical compound will have any particular therapeutic effect. This doubt can be substantiated by the verifiable fact that most chemicals don't, in fact, cure cancer. Therefore, in order to satisfy the sufficiency requirement, more evidence is needed to support a claim for a therapeutic use invention than would be needed to satisfy the sufficiency requirement for a mechanical invention. 

The higher level of underlying doubt surrounding therapeutic use inventions finds its expression in the plausibility test. Thus, in order for a therapeutic use invention to be sufficiently disclosed, there must be sufficient information in the application as filed to render the therapeutic use "technically plausible" (CLBA, II-C-7.2.2(a)) ("therapeutic use plausibility"). In other words, the applicant must provide sufficient evidence to overcome the high level of underlying doubt that a new drug will have a therapeutic effect. 

Critically, therefore, the plausibility test is not a higher sufficiency bar for therapeutic inventions. The sufficiency requirement, of there not being substantiated doubt that the invention will work, remains the same. What changes for therapeutic inventions is just the underlying level of doubt with respect to the invention, and thus the amount of evidence needed to overcome this doubt. 

The recent decision T 1571/19 considered the sufficiency for a therapeutic use claim, making use of the plausibility test. The patent as granted (EP2914124claimed a fish food for use in the treatment of diseases in fish. A skilled person would know that most fish food does not treat or prevent disease in fish, and as such there was a high level of underlying doubt with respect to the invention. However, the patent included data for a trial in which two example compositions were administered to fish. The Opponent argued that whilst the data showed some beneficial effects to begin with, these faded to below statistical significance, and so the claimed therapeutic effect was not plausible. However, the Board of Appeal were satisfied that the initial beneficial effects observed contributed to an overall picture that made the claimed therapeutic effect credible. For the Board of Appeal, the Opponent was unable to point to evidence of serious doubts with respect to the claimed therapeutic effect in view of this evidence. The claims were thus found sufficiently disclosed in view of the plausible therapeutic effect. Plausibility equated to a lack of doubts, substantiated by verifiable facts, that the skilled person would be able to work the invention. 

Whole range plausibility (Wind turbines, T 0500/20)

Another type of invention for which there may be a higher level of underlying doubt about whether the invention can be worked by a skilled person are inventions involving broadly claimed features. These broad features may be broad ranges of parameter values, functional features, or a broad genus of compounds. In such cases, there may be a high level of underlying doubt that a skilled person would be able to work the invention across the full scope of the broadly claimed feature (CLBA, II-C 5.4). For an invention relating to a broad range or class of compounds for which there is this high level of underlying doubt, the concept of plausibility is again employed. Thus, in order for an invention comprising a broadly claimed feature to be considered sufficiently disclosed, the application as filed must provide sufficient evidence to make it at least plausible that a skilled person would be able to work the invention across the whole range of the claim (CLBA, II-C 5.4) ("whole range plausibility"). 

In most cases, one example is sufficient

The Board of Appeal decisions in T 0500/20 and T 2773/18, both relating to wind-turbines, confirmed that whole range plausibility only applies to certain types of invention. When considering the sufficiency of the claim, the Board of Appeal found that the whole range plausibility test should only be applied to inventions in which a central aspect of the claimed invention is a range of compositions or of parameter values, e.g. inventions primarily in the chemical field for which there is a high level of underlying doubt that a skilled person could work the invention across the whole range. By contrast, as stated by the Board of Appeal in T 0500/20"[i]n claimed inventions that do not involve a range of parameter values or compositions basing an argument of insufficiency on this approach is inappropriate and can be rejected offhand for that reason."

In this Kat's view, therapeutic use plausibility and whole range plausibility are clearly synonymous concepts. In both cases, the concept of plausibility is introduced when there is a higher level of underlying doubt about an invention. Similarly, in both cases, the sufficiency test of whether there are substantiated doubts about the invention remains the same. The concept of plausibility is thus employed in cases where there is a higher level of underlying doubt in the field of the invention.

Plausibility in inventive step

The EPO also employs the concept of plausibility in the inventive step analysis of certain types of invention. But how does a concept relating to the sufficiency of evidence find its way into inventive step analysis under Article 56 EPC

The answer to this question is simple: If a functional effect of an invention is explicitly specified in a claim (e.g. "wherein the drug treats the disease"), the question of whether there is sufficient evidence for this effect is considered under the heading of sufficiency. In other words, the question is whether the application as filed provides sufficient evidence such that a skilled person can work the invention (Article 83 EPC). If the functional or technical effect of an invention is not expressed in a claim, but contributes to the problem the invention purports to solve (e.g. the functional properties of a new chemical compound), the question of whether there is sufficient evidence for the technical effect is considered under inventive step (Article 56 EPC) (CLBA, I-D-4.3.1). In other words, the question becomes whether there is sufficient evidence to convince a skilled person that the invention does actually solve the problem it purports to solve (T 0939/92, G 1/03)

There is usually little doubt as to whether an invention actually solves the problem it purports to solve. In the case of a widget, the description will describe the widget and provide an example of how it works and solves the problem. For other types of invention, however, there is more doubt about whether the invention has in fact solved the problem it purports to solve. This is particularly the case where the invention as claimed specifies a broad range of parameters. For such inventions, there may be doubt as to whether the invention solves the problem it purports to solve across the whole range of the claim.

The higher level of underlying doubt about whether certain inventions solve the problem they purport to solve across the whole range of the claim again finds its expression in the whole range plausibility test. Thus, in order for an invention to be considered to involve an inventive step, the application as filed must provide sufficient evidence to make it at least plausible that the invention solves the problem it purports to solve (CLBA, I-D-4.3.1I-D-4.3.3). Yet again, the plausibility requirement in inventive step is an expression of a higher level of doubt with respect to certain inventions and, for inventive step, whether or not they actually solve the problem they purport to solve. 

Final thoughts

Sir Robin Jacob's opined that plausibility was a Humpty-Dumpty-ish concept. In Lewis Carroll's Alice Through the Looking Glass, the character of Humpty Dumpty redefines the meaning of words with careless abandon. To Humpty Dumpty, words mean what you want them to mean when you want them to mean it, irrespective of established definitions. In this Kat's opinion, the EPO broadly speaking does not play Humpty Dumpty with the word "plausibility". At least as far as the established case law of the Boards of Appeal is concerned, plausibility has a consistent meaning in all of the contexts in which it appears (this Kat will leave the use of plausibility in the national courts for another day...).

The concept of plausibility is used consistently by the EPO as a way of acknowledging a higher level of doubt about certain types of invention. Crucially, the sufficiency test, i.e. that there are no substantiated doubts about an invention or its technical effect, always remains the same. What changes for different types of invention is the level of underlying substantiated doubt. It is therefore not surprising that the preliminary opinion of the EBA in G2/21 made reference to the test of whether there were serious doubts, substantiated by verifiable facts, that the invention in question solved the problem it was purported to have solved. The question of plausibility will always be one of whether there is sufficient evidence to overcome a high level of underlying substantiated and verifiable doubt about an invention and its technical effect. Plausibility is therefore not a new or additional requirement for patentability, but merely an acknowledgement of the technical challenge and complexity of certain categories of invention. 

Further reading

Plausibility demystified - a review of EPO case law before G 2/21 Plausibility demystified  - a review of EPO case law before G 2/21 Reviewed by Rose Hughes on Friday, February 24, 2023 Rating: 5

7 comments:

  1. Thanks for an excellent paper which shows actually that sufficiency is actually not dependent from the technical domain of the invention.

    A decision on sufficiency actually turns ought to decide whether there is a higher level of underlying doubt in the field of the invention. That this might be higher in the medical field than in other fields does not come as a surprise.

    That sufficiency can also plays a role when assessing inventive step is not only shown in G 1/03 but also in T 2001/12 as well as in T 847/14 and T 1469/16.

    If an effect is claimed, then sufficiently applies if there are doubts about obtaining the claimed effect.
    If an effect is not claimed, then sufficiently does not apply but inventive step applies if there are doubts about obtaining the alleged effect disclosed in the description.

    In T 847/14, the effect was not claimed and there was no lack of inventive step.
    In T 1469/16, the effect was not claimed but there was lack of inventive step.

    The EBA wants to limit its conclusions to the assessment of inventive step vs. post-published evidence and does not want to go further than this, cf. Point 14 in the Communication of the EBA. This is a pity as there is a link between sufficiency and inventive step, which is whether an effect is claimed or not.

    I would also like to refer to T 488/16 (Dasatinib 1) and T 950/13 (Dasatinib 2).

    T 488/16 (Dasatinib 1), quoted in the decision to refer, plausibility was not given and could not be supported by post-published evidence.
    In T 950/13 (Dasatinib 2), not quoted in the decision to refer, plausibility was given and could be supported by post-published evidence.
    And yet in both cases the same compound is at stake.

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  2. What might explain the drip-drip of derogatory remarks from England, about the established case law of the EPO Boards? Perhaps a gulf of difference between civil law and English common law fact-finding?

    Not only do we have EPO jurisprudence on Art 52 EPC patent-eligibility dismised as "intellectually dishonest". For Art 56, EPC, we have dismissive attitudes to the value of that beautiful tool for keeping impermissible hindsight out of the obviousness analysis, the "objective technical problem". And now we have the powerfully effective notion of "plausibility" condescendingly dismissed as Humpty-Dumpty lack of rigour. Thank you, Rose, for providing a defence of EPO jurisprudence.

    My explanation for the patronising attitudes given out by common law commentators is the different way facts are found, in England. One can see it every time one reads a written decision. An EPO tribunal can "don the mantle" of the person skilled in the art, an English judge not. The only facts in the dispute that an English judge can use for crafting the judgement are facts proved in evidence. Could it be that this handicap explains why concepts like "technical character", "plausible", "objective problem", so easy for an EPO tribunal to use as the core of their judgment, do not lend themselves to English-style fact-finding and so are not helpful for English judges striving to do justice between the parties in dispute.

    Nevertheless, common law fact-finding can be a more powerful tool than anything else, for "keeping a litigant honest". For that tool no longer to be available to a litigant would, I think, do real damage to the quality of patent litigation in Europe. For that reason, I am pessimistic about the UPC jurisprudence to come. At least at the EPO, the Boards are heavily influenced by English judgements and legal thinking. Far more, I suspect, than the UPC judges will be.

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  3. Dear Max Drei,

    As far as derogatory remarks and patronising attitudes are concerned, one prime example is given by the person finding that the way plausibility is dealt with at the EPO being "Humpty-Dumpty-ish".

    In a well-known video with Lord Neuberger about the famous “pemetrexed disodium” case he allowed himself to say in a very derogatory way that the examiner was “manifestly wrong” when raising an objection under Art 123(2) for a general claim for pemetrexed. Lord Neuberger did the same in his decision. This simply showed that those persons were not aware of the actual case law of the EBA and the BA in matters of added subject-matter.

    I would thus take the "Humpty-Dumpty-ish" comment, as coming from someone who is not well versed in the EPO’s boards of appeal case law and EPO procedures, with a bit more than a pinch of salt.

    As far as fact finding is concerned, it is clear that the way it is done at the EPO and in common-law are quite different. I would not say that litigants in opposition at the EPO are less honest, simply cross-examination à la UK is not practised. Even at the time when the UK was still participating in the UPC it was clear that cross-examination was not envisaged. If before the UPC a witness statement is not challenged before the panel, it becomes a fact. We are then a long way away from the common law approach.

    Remember that at the EPO a witness can be requested to repeat his judgement before a national court in his country of residence, albeit when residing in an EPC member state, but this is a very strong tool, which at times can be extremely efficient. I have seen it myself. and on top of it there is the free evaluation of evidence at the EPO.

    The problem is that with OP by ViCo, there is no guarantee that the witness is not listening into the OP before being heard. This is a big problem, the EPO is carefully ignoring.

    At the UPC, we will have to wait until the Court of Appeal has taken decisions. it is to be expected, especially in panels with two local judges, that national legal traditions will be pursued, at least in the beginning.

    Only at the Central division and at the Court of appeal there will be technical judges. It can thus be hoped that the opinion of technical judges will be given an appropriate weight when a decision is taken. But nothing is sure.

    At a local/regional court, the presence of a technical judge is not mandatory. At the EPO, technical boards of appeal always comprise a majority of technical judges. This will never be the case at the UPC.

    In general people have been bread in a common law environment are very keen to see any new position taken by a board in a decision to become the new standard. We have seen this recently in the discussions about the adaptation of the description. But it is not my intention to open this box again. It is just an example.

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  4. Plausibility has had a huge impact in oppositions in the last 10 years in the field of biotechnology. It has opened up the possibility of attacking the data in the specification, without needing to provide any evidence that the invention does not work. In reality the burden of proof has shifted to the patentee showing the data is good enough. That must have been unforeseen when the plausibility requirement was developed, and the Enlarged Board must now fix this

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  5. Everything is plausible unless proven implausible. For an allegation of insufficiency, one has to prove serious doubts as to the repeatability of the SM claimed. Same standard applies for an allegation that a purported technical effect is not achieved in a certain area of the SM claimed. Verifiable facts have to be shown by the one who negates. To apply this standard, neither an additional concept of “plausibility” is needed, nor serious doubts, if based on verifiable facts, will be dissipated by filing “other facts”. Absolute proof is not asked for. Neither serious doubts is about the amounts of experimental evidence that one is able to file with the EPO, nor the EPO is an agency for evaluation of clinical data.

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    Replies
    1. Dear Anonymous of Monday, 27 February 2023 at 23:23:00 GMT

      I think you will find that in an opposition you can simply state the specification does not contain any data that shows x, y, z, technical effects have been achieved. This can be a very potent attack and does not need any serious doubts and verifiably facts. It would be close to impossible to run this attack before plausibility became available as a new attack

      Thanks

      Delete
  6. The comments so far prompt me to try again.

    On reflection, perhaps Robin Jacob's "Humpty-Dumpty" comment is more useful than I first thought. Perhaps it reflects the different role of the court in civil law jurisdictions, compared with Robin's home jurisdiction, England, where the judge is deemed to know nothing "technical" and must craft a judgement exclusively from the technical facts proven in evidence in front of his nose, by cross-examination of the technical expert witnesses put forward by each of the opposing parties. The judge must prefer the evidence proffered by one of those experts over that given by the other. One of them is right, the other not. In contrast, a tribunal at the EPO reles on its own expert technical knowledge when finding "the facts". They are free to find as fact something a bit different from what either of the experts is pushing. So, of course, to an English litigastor, it seems like the judge sitting on their (gender!) high perch in any civil law jurisdiction is playing at being Humpty-Dumpty.

    At root, both legal systems though are deciding facts to a "more likely than not" standard, are they not? What could be more fitting, to such a standard, than the concept of "plausibility"? Not only at the EPO but also in England. The problem for English jurists might be that fact-finding is thought of as a binary process: either the fact is found, or it is not. Funny really, when one reflects that Englisgh law is notorious for everything being expresed in shades of grey whereas in a jurisdiction like Germany, the instinct is more to think binary, as in, yes, this is fact and, no, that is not a fact.

    One hopes though that in the end, common sense amongst judges, wherever they practise, will bring them to much the same conclusion, when under the EPC two parties in dispute go to court on the mainland or when they do it on an offshore island.

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