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G 2/21 – Plausibility or not plausibility? – That is the question!

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This decision was long awaited as the OP took place on 24.11.2022.

The patent relates to compositions exhibiting inseciticidal action, which comprise compounds represented by a general formula [Ia] or salts thereof and thiamethoxam and to methods for controlling insect pests by use of a mixture of said compounds.

Brief outline of the case

The opponent appealed the OD’s decision to reject the opposition.

During the appeal procedure the opponent relied on post-published evidence for inventive step, namely D23 (test   data), which the referring board decided to admit into the proceedings on procedural grounds. The tests of the opponent showed no synergistic effect.    

For inventive step, the patent proprietor relied on, inter alia, post-published evidence D21 (test data) in support of a synergistic effect.

In view of the parties’ different positions on the applicability of the so-called plausibility case law, both formulated opposing requests as to whether post-published evidence D21 should be taken into consideration.

The referring board concluded that, if only the data in the patent and D23 were taken into account, the patent proprietor’s MR would not be allowable.

However, if D21 was also to be taken into account, the patent proprietor’s MR would be allowable as the post-published experimental data in D21 were the only but crucial proof for the alleged synergy effect.

Summary of the questions referred to by the board

  1. Should post-published evidence be disregarded on the ground that the proof of a technical effect rests exclusively on post-published evidence? 
  2. Can post-published evidence be taken into account if an effect was plausible from the application as filed (“ab initio plausibility“)?
  3. Can post-published evidence be taken into consideration if there would have been no reason to consider an effect implausible from the application as filed (“ab initio implausibility“)?

Submissions on admissibility and relating to the questions referred


Some submissions were considering that the referral was not admissible, some suggested that sufficiency was also a topic concerned by the referral. Most considered it admissible.  

Question 1 – Free evaluation of evidence

As far as question 1, does the principle of free evidence allows to take into account post-published evidence, was concerned, there were some submissions denying the possibility of taking into account post-published evidence as a matter of principle, mainly for reasons of legal certainty.

Other submissions were such that the free evaluation of evidence should be maintained, albeit with reservations.

Question 2 – Ab-initio plausibility

Most submissions considered that post-published submissions could be accepted to confirm an effect, but an alleged technical effect has to be shown on the basis of the content of the application as filed in combination with common general knowledge.  A lack of such disclosure could not be made up for at a later stage by submitting post-published evidence showing that the alleged technical effect was indeed   achieved. The disclosure at the filing date should at least be credible.

The proprietor submitted that the approach underlying question 2 was at most applicable for the assessment of sufficiency of disclosure in particular where the technical effect was stated in the claim. It   should, however, not be applied to the assessment of inventive step because it would be extremely disproportional in terms of the legal effect, the awareness of the patent applicant and the burden of proof.

Question 3 – No ab initio implausibility

One set of submissions can be considered to be in favour of taking into consideration post-published evidence as a proof of an asserted technical effect if, based on the information in the application or on common general knowledge, the skilled person would have seen no reason to consider the effect noncredible.

In this vein, one submission considered that it should suffice if the technical effect ultimately relied upon was merely “not completely implausible”, especially bearing in mind that at the filing date the applicant may not know the closest prior art from which  the claimed invention must be distinguished.

On the other hand, the approach underlying question 3 was considered negatively as it lowered the threshold to patentability significantly and allowed for patents to be granted on the basis of, at the filing date, a merely speculative technical effect.

The EBA’s position


The EBA considered the referral admissible, but was of the opinion that the questions referred were only linked with IS and have nothing to do with sufficiency, since the referring board had accepted that sufficiency was given.

The EBA also decided that the questions would not be reformulated or reordered.

Use at the EPO of the problem-solution approach and its consequences on a possible technical effect

The EBA reminded that in order to assess inventive step, the boards of appeal and the administrative departments of the EPO use the “problem-solution approach“. The EBA especially drew the attention to the determination of the objective technical problem resulting from the difference of the claimed subject-matter with the closest prior art and the effect of the difference.

The technical problem must be derived from effects directly and causally related to the technical features of the claimed invention.

An effect could not be validly used in the formulation of the technical problem if the effect required additional information not at the disposal of the skilled person even after taking into account the content of the application in question.

Free evaluation of evidence

For the EBA, evidence submitted by an 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.

The EBA added that the judge must put all the arguments for and against a factual statement in relation to the required standard of proof. In doing so, the judge remains bound by the laws of the logic and by probability based on experience. The reasons that led the judge to be convinced of the correctness or incorrectness of a contested allegation as to fact are to be set out in the decision.

The deciding bodies under the EPC have the power and the duty to assess whether the alleged facts are sufficiently established on a case-by-case basis.

Free evaluation of admissibly filed evidence relevant for deciding the case at hand means that there are no firm rules according to which certain types of evidence are, or are not, convincing.

After having looked at how the principle of free evaluation of evidence in the Contracting States, the EBA concluded that the principle of free evaluation of evidence qualifies as a universally applicable principle in assessing any means of evidence by a board of appeal.  

If post-published evidence is considered to lack prima facie relevance or is not required for the decision on the issue in question of the case at hand, there is no need for it to be taken into account by the competent board of appeal.

Analysis of case law of the boards in matters of plausibility

The EBA analysed the lines of case law developed by the boards in matters of plausibility of a technical effect for assessing inventive step.

When analysing this case law in the EBA concluded that the core issue rests with the    question of what the skilled mind understands at the filing date from the application as originally filed as the technical teaching of the claimed invention. This conclusion is irrespective of the conceptual terminologies for what questions 2 and 3 refer to as two distinct plausibility approaches. 

Analysis of case law of the boards in matters of sufficiency of disclosure  

The EBA concluded that reliance on post published evidence is much narrower   under sufficiency of disclosure compared to the situation under inventive step

The EBA noted that the proof of a claimed therapeutic effect has to be provided in the application as filed, in particular if, in the absence of experimental data in the application as filed, it would not be credible to the skilled person that the therapeutic    effect is achieved. A lack in this respect cannot be remedied by post-published evidence.

Analysis of national case law in matters of plausibility

The EBA recognised a certain degree of common ground that the courts of the EPC   Contracting States, when confronted with the examination of an asserted technical    effect in the assessment of inventive step relying on post-published evidence as proof of a technical effect take, duly into account what the person skilled in the art,     with common general knowledge, understand from the application as filed.

Plausibility or not plausibility? – That is the question 

For the EBA, the term “plausibility” found in the case law of the boards and relied upon by the referring board in questions 2 and 3 of the referral and the reasons for it, does not amount to a distinctive legal concept or a specific patent law requirement under the EPC, in particular under Art 56 and 83.

For the EBA, the term “plausibility” rather describes a generic catchword seized in the jurisprudence of the boards by some national courts and by users of the European patent system. That it is not a criterion found in the EPC is manifest, but the problem-solution approach is also not to be found in the EPC.

The general conclusion of the EBA

The EBA confirmed the general principle of free evaluation of evidence, according to which late-filed evidence provided in order to assess inventive step, cannot be disregarded as merely being late-filed.   

The EBA held that an 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. The EBA added that the technical effect cannot and “does not change the nature of the invention”.

The EBA added that it was aware of the abstractness of some of the aforementioned criteria.

However, the EBA considered that the guiding principles it has set out should allow the competent board of appeal or other deciding body to take a decision on whether or not post-published evidence may or may not be relied upon in support of an asserted   technical effect when deciding on inventive step.


The final position of the EBA was already contained in its communication of 13.10.2022.

Looking at the decision of the EBA, one possible conclusion is that the term “plausibility”, which was a convenient concept used by the boards and national courts, should not be used any more.

At best, and already hinted at in the communication of 13.10.2022, it is the notion of ab-initio implausibility which seems to have been determining, whilst the EBA refused to give an answer to questions 2 and 3 from the referring board.

In general, the notion of “plausibility” is to be replaced by the following criteria:

  • an effect supporting inventive step should be “encompassed by the technical teaching” and
  • should be “embodied by the same invention” as originally disclosed in the application as filed.

That those two notions/criteria will give raise to a “dynamic interpretations” of the decision and of the criteria set out is more than probable.

It is a euphemism when the EBA adds that it was aware of the abstractness of the new criteria.

Normally decisions of the EBA are meant to clarify a legally confuse situation. Strong doubts are permitted whether G 2/21 answers this fundamental requirement.

That evidence has to be admitted in the procedure before being decided as to its substance goes without saying, but is a formal reason allowing boards not to admit late-filed evidence under the RPBA20.

It is clear that when applying the problem-solution approach, the technical effect which results from the differences between the closest prior art and the subject-matter claimed might not necessarily be the one relied upon originally by the inventor.

However, when a (therapeutic) effect is claimed as such, then the (therapeutic) effect is a functional feature of the claim and cannot be ignored.

The refusal of the EBA to extend its considerations to sufficiency is regrettable.

In G 1/03, OJ 2004, 413, Points 2.5.2 the EBA held that, depending on whether or not an effect is claimed the objection can change when there is lack of reproducibility of the claimed invention:

  • If an effect is expressed in a claim, there is lack of sufficient disclosure.
  • Otherwise, i.e. if the effect is not expressed in a claim but is part of the problem to be solved, there is a problem of inventive step.

T 2001/12 confirmed by T 847/14 and T 1469/16 has exemplified what was said in G 1/03. In view of this line of case law it is difficult to follow that reliance on post published evidence is much narrower under sufficiency of disclosure than under inventive step.

It might be worth drawing the attention to other decisions in which contrary statements had been made by the proprietor and the opponent.  

In case of contradictory assertions by the parties, albeit in matters of sufficiency, whereby the Office is not in a position to decide, then the benefit of the doubt goes to the proprietor, cf. T 72/04, Reasons. 3., last but one §, or T 1598/15, Reasons 1.3.

Why could not what is valid for sufficiency be applied to inventive step?


13 replies on “G 2/21 – Plausibility or not plausibility? – That is the question!”

Max Dreisays:

Daniel, thanks for getting your thoughts out so fast. In reply to your comments, I have two thoughts.

Why was the EBA so coy on Art 83? Well, the Supreme Court of the USA is (to the astonishment of many observers) currently engaged with the issue of “sufficiency”. It would not surprise me if, at the level of the EBA, it is seen as prudent/convenient, to let the USA “go first”. Then the EBA can write a decision that explains to the whole world (including the USA) the right way to manage the issue of sufficiency.

As to differences between Art 83 and Art 84 in relation to post-filed evidence, perhaps it can be explained on “public policy” grounds. To allow a “second medical use” claim through to issue is to encourage innovation in a field vital to human health. But to allow an obvious claim to survive is to hinder rather than encourage investment, in all fields of technical innovation

Avatar photoDaniel X. Thomassays:

Dear Max Drei,

As fair as getting thoughts in fast mode, Rose Hughes on IPKat and Laurent Teyssèdre on Le Blog were quicker.

It is an interesting thought about what is going on at the US Supreme Court. I do however have some doubts about the EBA waiting for the USSC to give an idea of what is to be understood under sufficiency.

It would actually need a further referral linking sufficiency with post-published evidence for the EBA to come to a decision on this topic. I fear that with the same rapporteur, plausibility would as well be put under the carpet for the same reasons as it has been done in G 2/21. We would most probably end up with a similar level of abstraction for the criteria to be used.

I agree with you that claims for second medical uses are very important as they can have a direct impact on human health. To my knowledge, the claim for a second medical use ought to define, for instance, the other illnesses to be covered, the dosage regimen or a new distinct group of patients. Such indications ought to be found in the claim as functional feature which is necessarily limiting.

According to G 1/03, if the purported aim is not credibly achievable the right objection is lack of sufficiency and not lack of inventive step, even if post-published is needed.

If the claim does not contain the purported aim, the claim is lacking an essential feature and is thus unclear in the meaning of Art 84, first sentence.

Max Dreisays:

Thanks for that reply, Daniel. Your thoughts are composed, mine not. Mine are not so much “abstract” as erratic. Nevertheless, I post them, because I like learning from your replies.

Still searching for reasons why the EBA didn’t take the chance to deal with plausibility and Art 83, it occurs to me that it might have to do with the question of “the benefit of the doubt” and whether Applicant should be allowed to enjoy it.

Perhaps the scholarly literature contains argumentation why it is right to give Applicant the benefit of the doubt under Art 83 but not Art 56. With the passage of time, claimed subject matter gets more obvious (ie failing the EPC test for patentability) whereas with time a claimed concept gets easier to put into effect on the basis of the as-filed description (ie passing the EPC test for patentability). So, running with a less strict Art 83 test has less severe consequences than being over-generous to Applicant on the Art 56 test of patentability.

Avatar photoDaniel X. Thomassays:

Dear Max Drei,

Your thoughts about a link between Art 56 and 83 are already embodied in G 1/03 and T 2001/12 as I have explained in my post.

There is a further decision I would here like to refer to: T 59/08. The conclusion drawn by the board in this case is interesting. The Board considered that less stringent requirements for assessing sufficiency of disclosure of the claimed combination of features would on the other hand require stronger arguments in favour of novelty and inventive step, especially if some parameter values are necessary to distinguish the claimed subject-matter from the prior art and considered essential for providing a technical effect vis-à-vis the prior art. See Point 2.7 of the reasons.

Another interesting decision is T 1036/09. Although an effect is claimed, and hence the objection should be, according to G 1/03, lack of sufficiency, the board was however of the opinion that it was more appropriate to consider the critical issue of the present appeal proceedings under the requirements of Art 100(a) /Art 56. See Point 4. of the reasons.

There is thus a series of decisions which show that strictly keeping out of sufficiency when dealing with post-published evidence was not the best position to be adopted by the EBA.

As far as the notion of benefit of the doubt should is concerned, this is nothing new at the EPO. This has always been the case for the party which does not have the onus of proof, i.e. in opposition, the proprietor. See for instance T 658/90. It is however not always the applicant/proprietor which has the benefit of the doubt. If an application has been refused, the patent has been revoked or a set of claims has been deemed not allowable, the onus of proof in appeal is reversed.

Max Dreisays:

Daniel, on the one hand, I ought to read the decisions you cite before I venture to reply but, on the other hand, it is more fun just to keep asking you questions. I think that “burden of proof” and “benefit of the doubt” are distinctly different legal concepts.

On this thing called “the benefit of the doubt” I think it might make a difference whether the proceedings are ex Parte or inter Partes contested proceedings. Particularly on the issue of sufficiency, the Office is at a disadvantage, if it has doubts about the compliance of a patent application with Art 83. So, in reality, it has no alternative than to give Applicant the benefit of the doubt. I suppose it is very different in opposition proceedings, when two big pharma concerns go head to head on Art 83. With “equality of arms” between the parties, the tribunal can impose on Opponent whatever standard of evidence it chooses.

One thing has always intrigued me and that is with Art 56 objections to a pending application. In the USA, the idea is that you get a patent unless the Office can establish that the claim is obvious. In a way, Applicant gets the benefit of any doubt.

But under the EPC, Art 52, Applicant has to satisfy the Office that the claimed subject matter is inventive. Does that mean that an Applicant at the EPO does not enjoy any “benefit of the doubt” under Art 56 and, instead has the burden to demonstrate the presence of inventive activity?

Avatar photoDaniel X. Thomassays:

Dear Max Drei,

There is certainly no reason, and even less an obligation, to look at the decisions I quote. I quote decisions I know about and could confirm or infirm what I can say. As far as the discussion is concerned, it does not really matter whether you have read them or not. In general, I have quoted those decisions in presentations on various topics about EPO procedures I have in store. May be the day I stop dealing with patents, I should publish them all.

I agree with you that “burden of proof” and “benefit of the doubt” are distinctly different legal concepts.

As far as Art 83 is concerned, there is little an ED can do when it comes to doubts on sufficiency. Unless the application goes again well-established laws of physics (just think of perpetuum mobile) or chemistry, or the problem meant to be solved is not credibly solved, there is little to be done.

May be, if the invention is defined by an unknown parameter and there is no method of measurement of said parameter, then an objection on Art 83 could be raised. But even there the case law of the boards is not uniform. For certain boards it is a problem of Art 84 rather than Art 83, especially when it comes to opposition. G 3/14 is then a good reason for a board not to go any further..

It is indeed only in opposition, when an opponent comes with experimental data that an objection under Art 83 can be pursued and examined, if it is not a hidden clarity attack. Without experimental data in opposition, it is however rather rare that the ground under Art 100(b) is at all successful.

As far as Art 56 is concerned, I cannot see any difference with the USA. A refusal under Art 56 has to be properly reasoned like for any other ground for refusal. If the refusal is not properly reasoned, cf. Rule 111(2), for instance arguments of the applicant have been ignored and not discussed in the decision, a board considers that the ED has committed a substantial procedural violation. See for instance T 1214/21 or T 1787/16.

If the ED has simply erred in the technical appreciation of the prior art, this would pertain to an error of judgement rather than to a procedural violation. Case law is very clear on this point. See for instance T 2662/16, T 2643/17 or J 12/19 for the Legal Department.

I would allow myself to say that the applicant has the benefit of doubt more than often. This is for instance the case when the opponent achieves a revocation or a limitation on the basis of documents mentioned in the search report drawn up by the EPO. We will however never know for sure whether the applicant has benefited from the doubt which is a reason you can see in the “internal votum” in which the first examiner explains to the two other members why he considers the claims allowable. The votum is, by a very old decision of the president, excluded from public inspection.

It is not really logical to see the reasons for a refusal in the public part of the file, but not the reasons why the first examiner proposed grant and the other members ageed. There have been suggestions to make the votum public, but I know for a fact that epi opposed it as it could prejudice the grant in other countries, guess which one: the USA.

francis hagelsays:

As to Art 83, the EPO’s unofficial policy is as DXThomas explains. EDs are not really supposed to raise Art 83 objections (except perhaps in pharma & chemical cases, but I am not sure, this is not my field of practice), and it is left to third parties observations or oppositions to raise this issue, in which case the arguments rely on the specialised expertise of third parties.
Looking at the Guidelines, the Art 83 section is remarkably succinct, compared to the Art 84 section.

There are reasons for that. A sufficiency objection may raise the technically difficult question of ascertaining the common knowledge of the skilled person at the filing date. This usually calls for a report by an expert of the field. This was the case in T 1173/00, reported in the 2004 EPO OJ. But this was in appeal after opposition.

In addition, an Art 83 objection can be seen as applicant-unfriendly, since any addition of information to the description would be inadmissible. In other words, a lethal weapon.

The way I have noted to circumvent these factors is for the ED to treat an Art 83 issue by an inventive step objection pointing out the absence of a technical effect, or by Art 84 objections.

Interestingly enough, BOAs decisions T 161/18 and T 1191/19 have raised the Art 83 issue ex officio in AI cases in which the description did not provide sufficient disclosure as to how the training datasets could be obtained. But the current draft Guidelines do not refer to this issue and do not mention the BOA decisions.

Avatar photoDaniel X. Thomassays:

Dear Mr Hagel,

As to Art 83, what I stated it is not the EPO’s unofficial policy. Simply it is very difficult for an ED to decide on the lack of sufficiency. In my last directorate we had to deal with mechanical perpetuum moble, so that I might have been more aware of the problem. As soon as the applicant explains that the device allows to gain more energy than is input, or that in first approximation friction can be neglected, it is clear that there is a problem of sufficiency.

The cases you mentioned, are really striking out like a sore thumb, and it was not so difficult to conclude on lack of sufficiency. T 1173/00 should never have been granted as it was manifestly speculative.

Art 84 is an objection should which should not necessarily be raised as long discussions may result. It is always better to give an interpretation of unclear features and object novelty or inventive step. With this kind of objections the applicant is in general obliged to argue much more convincingly than for clarity.

There is a very simple way to discriminate between Art 83 and Art 84. An Art 83 objection cannot be overcome without adding matter. As long as there is something in the original description, an objection under art 84 can be overcome. There is nothing unfriendly to the applicant in this way of doing.

It should be kept in mind that a feature lacking clarity does not help to establish novelty or inventive step as it does not allow to differentiate it from the prior art, cf. T 197/10 as example.

I don’t think you can generalise to say that “An Art 83 objection cannot be overcome without adding matter.” If the claim is not enabled across the full scope, the scope can be narrowed to correct the A83 objection. Like it was done in the main request of T 409/91 (Exxon fuel oils).

Avatar photoDaniel X. Thomassays:

Dear Layne,

You are absolutely right!

If indeed the claim can be limited, the objection under Art 83 can be overcome.

I had once a case in opposition in which the OD introduced ex officio the ground of opposition under Art 83.
The claim was so broad that it was about a bidirectional line transmitting an alarm signal. The problem was that the line was pulled to ground in case of an alarm. With a line pulled to ground no electric signal can ever be transmitted.
Once the claim had been limited to the a disclosed embodiment in which when the line was pulled to ground it triggered a circuit, the patent was maintained in amended form. The funny thing was that when the OD came with the objection, the opponent said: now we realise why the claimed device was not always working….

However an objection under Art 83 just against a claim as such is not the standard situation.
It is often a hidden clarity objection.

In general, as far as Art 83 is concerned, it is the whole description which is insufficient.

Then it is indeed not possible to overcome the objection without adding subject-matter.

Francis hagelsays:

I had talks over granted cases with experienced
examiners during the 2021 and 2022 SACEPO meetings of the working group on quality. One of them told me that in his decade-lond career, he had only seen 2 rejections based on Art 83.
With the other, I found blatant Art 83 in a case. He said this should not be highlighted in the formal presentation to SACEPO but it was preferable to refer to the issue under Art 56.

Avatar photoDaniel X. Thomassays:

Dear Mr Hagel,

I have no doubts about what examiners told you.

I happens that in my last directorate we had to deal with perpetuum mobile, IPC class F03G 7/10.
I have thus seen quite a few objections under Art 83.

What is interesting is that such applications are rarely refused under Art 83. They are more often refused under Art 123(2). Once told that their application is not conform with the laws of thermodynamics, such applicants come up with a wealth of further information in the description and in the claims.

In electronics I never saw objections and refusals under Art 83. In medical physics, I saw a few.

It all depends whether the claim refers to an effect or not that an objection under Art 56 is possible.

If the effect is claimed, then the objection is Art 83.
The objection can only be Art 56 if the effect is not claimed and the aim of the invention is not credibly achieved.

I refer here once again to G 1/03 and T 2001/12.

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