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EPO: New referral to the Enlarged Board of Appeal – post-filed experimental evidence and plausibility; G 2/21

At last: the long-awaited referral to the Enlarged Board of Appeal with respect to one of the most controversially discussed issues in EP patent matters in recent times, i.e. plausibility, is here. In the case T 116/18, the Board of Appeal decided to refer three questions of law to the Enlarged Board of Appeal regarding plausibility and post-filed evidence (G 2/21).

The referral is made on the background of the long-standing practice of the Boards of Appeal that experimental evidence for the technical effect defined by applying the problem-solution approach may be submitted and taken into account to establish an inventive step, even though this evidence is not part of the application as filed. This practice was evolved in cases where the problem underlying the invention had to be reformulated as compared to the initial problem named in the application because of prior art found during examination or opposition proceedings.

In the wake of this practice, some Boards requested that said technical effect, even though it was formulated after the filing date of the application in question, and based on hitherto uncited prior art, nevertheless must at least be rendered plausible by the application as filed. 

The Board in T 116/18 termed such technical effect rendered plausible by the application as filed as “ab-initio plausibility”. The Board of Appeal, however, also noted decisions in which this criterion for ab-initio plausibility was found to be incompatible with the problem solution approach because the applicant would be forced to cover a potentially extensive number of technical effects of an invention in the original application to ensure that these effects might later be taken into account when discussing inventive step.

The Board identified a further scenario it termed “ab initio implausibility”. In this scenario, the question to be asked would be whether there were any reasons based on the common general knowledge to assume that the alleged technical effect was not obtained.

The Board also asked whether it was equitable to allow an opponent to rely on post-published evidence if the patentee was denied reliance on post-filed evidence to support plausibility?

The Board concluded that the following questions on plausibility and post-filed evidence required a referral to the Enlarged Board of Appeal (summarized in our own words):
(1) Should post-filed data be disregarded if they are the sole evidence for a technical effect?
(2) Can post-filed data be taken into account if there is ab initio plausibility?
(3) Can post-filed data be taken into account if there is ab initio implausibility?

It remains to be seen whether the referral is admitted (already, there is breaking out a discussion in the blogs whether the referral might be inadmissible because there is, contrary to the Board´s finding, neither a point of law of fundamental importance nor diverging case law to be decided upon) and, if so, which path the Enlarged Board of Appeal will cut through the thicket of opinions on plausibility.

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Dr. Stefanie Parchmann


German Patent Attorney

European Patent Attorney