Enlarged Board of Appeal’s preliminary opinion on plausibility

In the “plausibility” referral G2/21 to the Enlarged Board of Appeal (EBA) of the EPO (EPO), the EBA has recently issued a preliminary opinion (see EPO register) in preparation for the oral proceedings scheduled for 24 November 2022.

The questions referred to the EBA sought guidance on the issue of whether post-published evidence (evidence published after the filing date of the application or patent) could always be relied on to prove a purported technical effect underlying the inventive step of an invention, or only when the technical effect would have been plausible or at least not implausible from the viewpoint of the skilled person based on information already contained in the application as filed (see our earlier post on this matter).

The EBA appears determined to provide clarity on this point of law, and hence intends to deem the referral admissible. Further, the EBA underscores the crucial importance of the principle of free evaluation of evidence for the parties’ right to be heard before the EPO, and does not seem prepared to tolerate any deviations from this principle.

That said, the EBA clearly appreciates the urgent need to provide reliable guidance on the plausibility issue in the framework of inventive step assessment.

The EBA’s position seems to be that the application as filed must allow the skilled person to identify the technical teaching of the claimed invention, and that any purported technical effect relied upon even at a later stage needs to be encompassed by that technical teaching and embody the same invention. This corresponds to the lowest “plausibility” approach as set forth by the referring Board – that the purported technical effect needs to be within the spirit of the originally claimed invention.

However, the EBA goes a step further and seems sympathetic to the option of disregarding post-published evidence in situations when the skilled person – based on evidence present in the application as filed and common general knowledge – would have had significant doubts in respect of the purported technical effect. This corresponds to the intermediate “ab initio implausibility” approach as set forth by the referring Board. In contrast, the EBA does not appear inclined to adopt the stricter “ab initio plausibility” approach, which would require any purported technical effect to be made plausible to the skilled person by the application as filed and common general knowledge.

While we all eagerly await the EBA’s decision, which will still take some months to arrive, if the EBA maintains its viewpoints, it remains key to include evidence of technical effects already in the application as filed, at least insofar the technical effects seem likely to be considered implausible by the skilled person (such as going against what could be expected based on established knowledge).