Armchair inventions part 3: Decision on plausibility at the EPO (G2/21)

The issue of plausibility was previously referred to the Enlarged Board of Appeal (EBA), the highest judicial authority at the European Patent Office (EPO). Our article on the referral can be found here. The oral proceedings for G2/21 took place in Munich on 24 November 2022 and our article summarising the preliminary opinion can be found here.  The final decision has now issued – and leaves plenty of room for interpretation.

Question 1: Principle of free evaluation of evidence

The first question considered by the EBA was whether, in a case where post-published evidence is the exclusive support for a technical effect when assessing inventive step, deviation from the principle of free evaluation of evidence should be allowed.

The EBA took the position that the principle of free evaluation of evidence must not be disregarded, stating: “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.”

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.

Questions 2 and 3: Plausibility

Referred Questions 2 and 3 were designed to address the relevance and standard of plausibility of disclosure of the patent application and - as phrased – were dependent on question 1 being answered in the affirmative.   As noted above, question 1 was answered in the negative – (free evaluation of evidence must not be disregarded) but the EBA, in any event, went on to review the case law on plausibility, and consider whether plausibility could play a part in admission of post-published data for assessment inventive step.

Even though the referral specifically considered plausibility only in the context of inventive step (Article 56 EPC), the EBA additionally reviewed the case law on sufficiency (Article 83 EPC), and it therefore appears that the decision could well be relevant to future decisions under both grounds.

Question 2 asked whether the technical effect has to be positively plausible (ab initio plausibility) based on the common general knowledge and teaching of the application at the filing date. Question 3 asked whether the technical effect has to be not implausible (ab initio implausibility), based on the common general knowledge and teaching of the application at the filing date.

In considering these two questions, the EBA concluded that plausibility, as such, is not a distinctive legal concept or a specific patent law requirement under the EPC, in particular, under Article 56 and 83 EPC.  For the EBA, the relevant standard for reliance on a purported technical effect when assessing inventive step rather concerned the question of what the skilled person, with the common general knowledge in mind, would understand at the filing date from the application as originally filed as the technical teaching of the claimed invention.

In short, the consideration of plausibility appears to be not the definitive legal test, and instead 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 consider said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention”.  

This assessment may then determine whether post-published evidence may or may not be relied upon in support of an asserted technical effect when assessing inventive step.

The exact meaning of the above will likely become a source of debate, as the requirement for the technical effect to be “encompassed” by the teaching and “embodied” by the invention appears somewhat vague. 

Conclusion

The decision of the EBA is clear on one point, in that post-published data, admitted as the sole evidence of a technical effect when assessing inventive step cannot be disregarded purely because it was not available at the filing date. However, the requirement for the technical effect to be “encompassed by the technical teaching and embodied by the same originally disclosed invention” is only loosely defined, a point effectively admitted by the EBA who conclude that, “The Enlarged Board is aware of the abstractness of some of the aforementioned criteria”. This is presumably deliberate, to allow for sufficient flexibility and discretion in future decision making for the Technical Boards of Appeal. Watch this space as applicants attempt to interpret this language to support their arguments.