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Read the Preliminary Opinion here.

The Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) has issued a Preliminary Opinion in the Plausibility referral G 2/21. Unsurprising is the EBA’s answer to the first question: post-published evidence submitted as the exclusive support of an alleged technical effect for inventive step should not be disregarded. More thought provoking, however, is the EBA’s answer with respect to when and how to use it (questions two and three): reliance on post-published evidence for establishing inventive step is permitted provided that (1) the technical effect relied upon is encompassed by the technical teaching in the application as filed and embodies the same invention and (2) there are no significant reasons to doubt it; however, if significant doubts exist reliance on the post-published evidence is ‘questionable’.

Of course, at this stage we have just the Preliminary Opinion, which is non-binding, and so close attention needs to be paid to both the Oral Proceedings set to take place on 24 November 2022, and to the ensuing decision which is expected in the first half of 2023. Further updates will be provided as developments occur.

In February 2022 we reported on the Written Decision issued in T 116/18, which confirmed the scope of the referral to the Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) regarding the use of post-published evidence for establishing a technical effect with respect to inventive step – the Plausibility referral, G2/21.

Since our article in February 2022, Oral Proceedings before the EBA have been scheduled for 24 November 2022 and a Preliminary Opinion has been issued.

In the Preliminary Opinion, the EBA acknowledged arguments regarding the wording and structure of the referred questions but confirmed their intention to proceed with the questions as drafted by Board 3.3.02 in T 116/18. The EBA could have redrafted the questions referred but chose not to.

By way of reminder, the questions referred to the EBA are as follows:

  1. Should an exception to the principle of free evaluation of evidence (see e.g. G 3/97, Reasons 5, and G 1/12, Reasons 31) be accepted in that post-published evidence must be disregarded on the ground that the proof of the effect rests exclusively on the post-published evidence?
  2. If the answer is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have considered the effect plausible (ab initio plausibility)
  3. If the answer to the first question is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have seen no reason to consider the effect implausible (ab initio implausibility)?

With respect to the first question, the EBA preliminarily opined that the principle of free evaluation of evidence, which entails a key rule of procedural law, does not allow disregarding such evidence per se and to do so would deprive the party submitting the evidence of a basic legal right enshrined in EPC Articles 113(1) – ‘right to be heard’ – and 117(1) – ‘means and taking of evidence’.

Thus, preliminarily, the EBA has answered question 1 in the negative. That is, post-published evidence submitted to establish a technical effect for inventive step cannot be disregarded, regardless of whether the technical effect rests exclusively on the post-published evidence.

What matters next is when and to what extent that evidence can be relied upon. With respect to questions 2 and 3, the EBA have preliminarily opined that reliance on post-published evidence for establishing inventive step is permitted provided that (1) the technical effect relied upon is encompassed by the technical teaching in the application as filed and embodies the same invention and (2) there are no significant reasons to doubt it; however, if significant doubts exist reliance on the post-published evidence is ‘questionable.’

Thus, preliminarily the EBA seem to be in favour of the ‘ab initio implausibility’ standard with the added two-part caveat that the technical teaching relied upon must be encompassed by the technical teaching in the application as filed and must embody the ‘same invention’. Whether this latter requirement signifies the introduction of a modified plausibility test remains to be clarified.

Of course, the concept of plausibility at the EPO is not limited to the realm of inventive step, it is a concept that is equally applicable to the determination of sufficiency of disclosure. That said, in the presently discussed Preliminary Opinion, the EBA has commented that the scope of the referral is limited to establishing the significance of post-published evidence relied upon in respect of a purported technical effect when assessing whether claimed subject matter involves an inventive step. Thus, whatever test is introduced by the EBA, a key follow-up question will be whether its subsequent application will indeed be limited to inventive step (as appears to be the EBAs intention) or will ultimately extend also to the assessment of plausibility with respect to sufficiency of disclosure (as the EBA’s test is applied by the Technical Boards of Appeal).

Having discussed the Preliminary Opinion, we wish to remind our readers that neither the opinions expressed, nor the positions taken, are binding and so close attention needs to be paid to both the Oral Proceedings set to take place on 24 November 2022, and to the ensuing decision which is expected in the first half of 2023.

Further developments will be reported as they arise.


Our articles are for general information only. They should not be considered specific legal advice, which is available upon request. All information in our articles is considered to be accurate at the date of publishing.

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