e) Hearing a witness before a national court 

Under R. 120 EPC, any party, witness or expert summoned to appear before the EPO can request authorisation to be heard by a competent court in the state in which they are resident (see, for example, T 582/90 and, by contrast, T 827/99, in which the witness's hearing by a national court was considered unnecessary).

In T 1043/93 a notarial statement by Italian witnesses duly summoned but not present was produced on the day of the oral proceedings before the board, with their age cited as the excuse for their failing to appear. The board observed that their age had already been known to the party and that the witnesses had not requested to be heard by the competent court of their country of residence (R. 72(2)(c) EPC 1973, now R. 118(2)(d) EPC).

In T 1551/14 the issue of the credibility of the witness, one of the appellant's employees, was critical since the points made by the witness in a statutory declaration regarding the new auxiliary request were of major importance for its patentability and had previously only been supported by that statutory declaration. For the board, this issue could only be settled by hearing the witness again, if necessary, under oath before a national court (R. 119 and 120(2) EPC). The case was remitted with an order to hear the witness in question.

In T 1117/16 during the opposition proceedings the witnesses had rejected the second invitation to give evidence, stating that they were not (or no longer) willing to do so. The appellant (opponent 1) claimed that the opposition division had committed a substantial procedural violation in deciding not to order that the witnesses offered as evidence in relation to the asserted public prior uses oV1 and oV2 be heard before a competent national court, even though it had deemed these public prior uses relevant and the witnesses would have been compelled to give evidence before that court. In the board's opinion, the wording of R. 120(1), second sentence, EPC did not create any legal obligation on the EPO to request that the competent court in a witness's country of residence as per Art. 131(2) EPC 1973 hears that witness – it merely gave the EPO discretion in this regard. Rule 120(1) EPC was not applicable in the case at issue, and under the provisions of the EPC nobody could be compelled to give evidence in proceedings before the EPO. The statement by the appellant's witnesses that they did not wish to give evidence might have been relevant for the evaluation of evidence, but it was immaterial for the issue of whether these witnesses needed to be heard before their competent national court. An advance for the expenses was also an issue.

Article 131(2) EPC provides the basis for evidence to be taken by national courts or other competent authorities of contracting states (see also R. 118(2)(d) EPC, R. 120 EPC, R. 150 EPC, and EPC Guidelines E‑IV, 3 – April 2025 version).