As William Blake put it in Auguries of Innocence, written in 1803 but not published until 1863, “A Robin Redbreast in a cage, puts all heaven in a rage”. So did the ill-crafted concept of plausibility with the case law of the EPO’s Technical Boards of Appeal (TBA). It introduced an artificial cage that trapped several TBAs – except those that were savvy enough to remain outside the cage (i.e. No plausibility) – causing a profound state of disarray in the TBAs’ case law. The cage was not only artificial but also, most likely, illegal. For no legal basis for this cage will be found in the text of European Patent Convention and/or its Implementing Regulations, let alone the text of the TRIPS Agreement, although the EPO is of course not technically bound by the latter.

Against this background, it is a matter for celebration that Decision G 0002/21 did away with what the Enlarged Board of Appeal (“EBA”), in par. 58 of this decision, labelled a “generic catchword” (i.e. plausibility). As readers are well aware, this so-called “generic catchword” gave rise to three different lines of case law (Ab initio plausibility, Ab initio implausibility and No plausibility) and, down the road, it caused a lot of damage to legal certainty. In this regard, in par. 72 of the decision, the EBA wrote that “[…] the Enlarged Board is satisfied that the outcome in each particular case would not have been different from the actual finding of the respective board of appeal.” Whilst it is understandable that an organ whose job is to keep things harmonized may not easily accept, even implicitly, that things were indeed disharmonized, it stands to reason that the EBA would not have responded to the questions sent by TBA 3.3.02 so carefully if the application of one line of case law or another would not have affected the conclusion reached in each individual case. Of course, it did. So, as mentioned above, it is a matter for celebration that plausibility has been consigned to history. As TBA 3.3.02 noted in par. 11.3.2 of its Decision T 0116/18, that is, the decision published after receiving the responses from the EBA:

In formulating order no. 2 in this way, the Enlarged Board did not refer to any of the plausibility standards identified by the board in its referring decision, either by mentioning these standards specifically or by using wording reflecting terminology underlying these standards. On the contrary, it used new legal terminology that had not been applied so far in the context of inventive step. The Enlarged Board may have chosen to do so for two reasons, namely either because it considered all three plausibility standards to be wrong and wanted them to be replaced with the requirement(s) of order no. 2, or because it considered all three standards to reflect the same requirement and wanted to condense this requirement by that (or those) defined in its order no. 2. The actual reason why the Enlarged Board formulated order no. 2 as it did may, however, be left unanswered. What matters is that when deciding whether a patent applicant or proprietor may rely on a purported technical effect for inventive step, it is the requirement(s) defined by the Enlarged Board in order no. 2 that has (have) to be applied, rather than simply using any rationale developed in the previous plausibility case law.

So, moving forward, TBAs will have to manoeuvre within the contours of the new test introduced by G 0002/21:

1. Evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgement of inventive step of the claimed subject-matter may not be disregarded solely on the ground that such evidence, on which the effect rests, had not been public before the filing date of the patent in suit and was filed after that date.

2. A patent applicant or proprietor may rely upon a technical effect for inventive step if the skilled person, having the common general knowledge in mind, and based on the application as originally filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.

Although it would have been preferable, instead of introducing a new test, to let the articles of the EPC do their job, the new test, as shown by the TBAs’ decisions following G 0002/21 to date, has shed more light. As the EBA pointed out in par. 95 of Decision G 0002/21, it is a rather abstract test. But this abstractness is precisely what it makes it capable of being of service to TBAs in resolving very diverse cases on their desk.

The Robin Redbreast is an absolutely beautiful bird that is not shy of humans and produces incredibly beautiful birdsong. The beauty of its singing is comparable to the beauty of the reasoning of Interlocutory Decision of 11 October 2021 from TBA 3.3.02 where, struggling to escape from the cage, after developing a thorough review of the three different lines of case law, it begged the EBA to put to an end what was a clear state of disarray. This author would not like to finish this entry without praising the diligence and sense of responsibility of TBA 3.3.02 for having flagged the dimension of a legal debate among various TBAs that had placed legal certainty at bay. Also, the legal grounds of Decision T 0116/18 of 28 July 2023 constitute an enlightening roadmap to navigate the certainly abstract waters of G 0002/21. In spite of its abstractness, to date, TBAs and most national courts have felt at ease charting waters under the new test.

All in all, notwithstanding the good intentions of the TBA that introduced the plausibility concept in Decision T 1329/04 (John Hopkins), an example of the Ab initio plausibility line of case law, experience has proven the damage that deviating from the text of the EPC can cause legal certainty. Time will confirm whether G 0002/21 has freed the Robin Redbreast from its cage.


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  1. Dear Mr Montana,

    I like your comparison with the Robin Redbreast, but I am not convinced that G 2/21 is as wonderful as you make out.

    When you look at decisions following G 2/21 it is possible to conclude that the latter has not brought what could be expected. In order to avoid the naughty word “plausibility” some decisions have now introduced the concept of “credibility”. Where is the gain?

    In G 2/21, the EBA refused as such to discuss sufficiency as this was not part of the questions referred by the board. It happens that there is a link between sufficiency and IS depending on whether an effect if claimed or not, see G 1/03 and T 2001/12.

    In T 728/21, relating to a composition under Art 54(5), sufficiency was at stake and G 2/21 was applied.

    Boards are already diverging in the application of G 2/21. Some boards consider that the effect does not have to be mentioned in the original specification, e.g. T 1989/19, whereas other considered that the effect has to be directly linked with the effect originally mentioned in order to be “encompassed”, e.g. T 681/21.

    I have difficulties with T 116/18 which was at the origin of G 2/21. In T 116/18, the buzzword was “synergy” and the whole discussion turned about replacing clothianidin by thiamethoxam. Although it can be accepted that the proprietor cannot be expected to have provided proof in the application as filed of the synergistic insecticidal effect for every conceivable combination of insecticides against every conceivable insect species, it remains that it was the action on a very specific insect which led to a broad claim. Where is the difference in the result with ab initio not implausibility?

    T 1989/19, relates to a pharmaceutical product (tiotropium), the only difference with the CPA was the water content. The water content increased the storage stability as there was necessary a lapse of time between the manufacture and the use of the product. The board accepted post published experimental data showing the storage stability. The whole thrust about patent was about stability during micronisation, not during storage. As the word “stability” was used, the BA accepted the post-published evidence about storage stability. It looks rather trivial that a pharmaceutical product has to be stable during storage. The buzzword “stability” was enough to admit the post-published evidence.

    In T 681/21, the synergy effect eventually claimed was different from the original synergy, and hence G 2/21 was not applicable. Here the buzzword “synergy” did, rightly, not help.

    In T 2716/19, the board admitted a post-published document the proprietor kept for 19 years before introducing it in the procedure. Is this reasonable?

    When looking already at a few decisions, it looks to me that it will very much depend on how G 2/21 will be applied by different boards. However, what applicants/proprietors on the one hand and opponents on the other hand, need is consistency. To me the case law on plausibility was, as a whole, consistent. When looking at the few decisions applying G 2/21, I am at a loss of finding legal certainty. Let’s hope that it will improve with time.

    I am happy for the applicants/proprietors which will benefit from it, but I am not so sure that G 2/21 will, at the end of the day, be a real progress.

    Last but not least, when you speak about concepts which are not mentioned in the EPC, I would like to draw your attention to the fact that the “problem-solution-approach” is not to be found in the EPC either. I do however observe that there are hardly no decisions of TBAs not using the “problem-solution-approach” when it comes to assessing IS. If you dislike “plausibility” for not being mentioned in the EPC, should also dislike the “problem-solution-approach”.

    1. Dear DXThomas,

      I tend to agree with your position that G2/21 did not provide enough clarity as was expected.

      When I read that the skilled person would “derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention”, it appears to me that
      1. the effect should “relate” to the disclosure (quite broad, but to avoid disclosing an herbicide and later trying to solve the problem of treating a human disease), and
      2. the effect should have been “concretized” in the disclosure.

      Whether “concretize” means having data showing the effect or merely having some prophetical examples with later shown data is still unclear.

      We should remember that G2/21 applies to all fields, including those where data is typically not required (e.g., mechanical inventions).

      Thank you Montana and DXThomas for the interesting discussion!

  2. I’m not a chemist so maybe I should refrain from commenting here, but it comes as a surprise to me that the notion of “plausibility” is flawed and deserves to be binned. I read DX Thomas above and find myself nodding along with everything he writes in this thread.

    Does anybody recall the uproar in the USA when it was proposed to sweep away its “First to Invent” law and replace it with a “First to File” system? There will be trouble, warned the nay-sayers and headless chickens. Corporations competing with each other will be obliged to file patent applications on the basis of speculation about technical effects, lest they get squeezed out of lucrative markets by the earlier filings of their competitors.

    Seasoned FtF practitioners told them they were worrying unnecessarily, that filing prematurely would end in tears. But that does nothing to alleviate the pressure on inventors to get the filing event just right, not a day too soon and not a day later than the moment when the case is fit to file. But when is a draft “oven ready”? For that, Applicants need guidance from the courts, legal certainty if you will.

    I’m with DX Thomas. Plausibility delivered that help to Applicants, to know when to file. Does G2/21 do anything to improve legal certainty (or the balance of power between filers and their compeitors)? I don’t see it yet.

    And if plausibility is rubbish, why did the courts in England embrace the concept?

  3. Dear Max Drei,

    Thanks for your comments.

    As far as Ftf is concerned, I would allow myself to add that even in the US 80% of the cases the Ftf was also the Fti. The US still do not have a Ftf in the same meaning as all other countries.

    I remeber old patents were there was even a time stamp on the application as filed.
    The likelihood that two applicants come up the same day with the same invention is so remote that the date stamp has been abandoned. That a group of applicants come up in a rather short time to the same ideas is however reality in certain fields. But for this we have Art 54(3) at the EPO.

    There is indeed a trade off between early filing and completeness of the invention.
    I agree that filing prematurely can “end in tears”.

    On the other hand, G 2/21 appears to be helping applicants/proprietors in an undue manner if the board is not careful about what is “encompassed and embodied by the same originally disclosed invention”.

  4. Thank you for your comments.

    You may wish to also read “Plausibility and policy”, published by Sir Robin Jacob in Bio-Science Law Review, vol. 17, Issue 6, p. 223-233. It addresses some of your points.

  5. Coming back to the thread, the thought that occurs is that the interests of justice are best served by taking care to preserve enough wiggle room for judges to get to the right answer, in the unique matrix of fact presented to them in each new case at bar. Perhaps the EBA’s seemingly fuzzy formulation:

    “……would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.”

    will turn out, in due course, to be in this way a helpful contribution to the jurisprudence, allowing litigants to assess with a higher level of confidence, which of the opposing sides is going to prevail, if the case goes all the way to the seized court of appeal.

    I used to think that the doctrine of binding precedent was essential to legal certainty but have come round to the view that greater levels of legal certainty arrive, admittedly over decades of case law, with the Darwinian (survival of the fittest line of case law) evolution of law of patents at the EPO. One hopes that it won’t all get screwed up by the UPC.

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