4.1.1 G 2/21: reasserting and refining the principle of free assessment of evidence

G 2/21 (OJ 2023, A85) addressed this principle and its consequences in detail, especially in points 27 to 46 of the Reasons, ruling on a referral that primarily concerned whether or not post-published evidence in support of the technical effect of an invention could be considered when examining inventive step.

G 2/21 provided an opportunity to explore once more how the principle operates, summarise the applicable case law and confirm certain aspects. Of particular note are the following findings from G 2/21, which are mainly to be found in points 27-46 and 55-56 of the Reasons:

The principle of free evaluation of evidence can be defined in abstract and general terms as allowing and, by the same token, requiring judicial bodies, such as the boards of appeal, to decide, at their own discretion and according to their own conviction, by taking account of the entire content of the parties' submissions and, where appropriate, any evidence admissibly submitted or taken, and without observing formal rules, whether a contested factual assertion is to be regarded as true or false.

This does not mean that the evaluation of the evidence can be arbitrary; rather, the evidence must be assessed comprehensively and dutifully. The only decisive factor is whether the judge is personally convinced of the truth of the factual allegation, i.e. how credible the judge classifies a piece of evidence. To do this, 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 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 principle of free evaluation of evidence cannot be used to disregard evidence per se where it has been admissibly submitted and relied upon by a party in support of a disputed inference and is decisive for the final decision. Disregarding it as a matter of principle would deprive the party submitting and relying on it of a basic legal procedural right generally recognised in the EPC contracting states and enshrined in Articles 113(1) and 117(1) EPC (see also T 1110/03, point 2 of the Reasons; T 1797/09, point 2.9 of the Reasons; T 419/12, point 2.1.3 of the Reasons; and T 2294/12, point 1.1.3 of the Reasons).

This definition likewise applies to decisions taken by the administrative departments of the EPO in patent granting procedures.

The deciding bodies under the EPC have the power and the duty to assess on a case-by-case basis whether the alleged facts are sufficiently established. By virtue of the principle of free evaluation of evidence, each body takes its decision on the basis of all the relevant evidence available in the proceedings, and in the light of the conviction that it has freely formed when evaluating whether an alleged fact is or is not to be regarded as true and proven. Free evaluation of admissibly filed evidence relevant for deciding the case in hand means that there are no firm rules according to which certain types of evidence are, or are not, convincing.

The Enlarged Board of Appeal in G 2/21 recalled the boards' existing case law on the evaluation of evidence in points 38 to 46 of the Reasons.

It concluded from this case law that the principle of free evaluation of evidence qualified as a principle universally applicable to the assessment of any means of evidence by a board of appeal.

Turning more specifically to the referred points of law, the Enlarged Board in this respect held in G 2/21 that 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 cannot be disregarded solely on the ground that this 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 Enlarged Board acknowledged a need to provide guidance on the application of the principle of free evaluation of evidence in respect of such post-published evidence relied on in support of a purported but contested technical effect.