2.4.4 Expert opinion submitted by a party

Following on from the section on expert opinions ordered by a board (Art. 117(1)(e) EPC), this section relates to expert opinions the parties themselves furnish as evidence (as occurs most often in practice).

In T 517/14 (priority right, Israeli law), with regard to an expert opinion submitted by the appellant the board noted that, while an opinion by an expert who has represented a party "in numerous proceedings" may, upon free evaluation of the evidence, have carried less weight than a court decision, another independent authority under the national law or an expert commissioned by the board under Art. 117(1)(e) EPC together with R. 117, first sentence, EPC, an opinion of a party's expert was a means of evidence under Art. 117(1) EPC.

In the following cases, the boards likewise dealt with expert opinions offered by a party: T 1676/08, T 658/04, T 885/02, T 276/07 (expert opinion not translated from Italian), T 74/00 (legal expert opinion, Japanese law), T 1201/14 (transfer of right of priority – US law, Taiwanese law); R 18/09 (external legal opinion on the admissibility of the petition), T 156/15 (opinion of a former board member submitted as expert evidence), T 2132/16 (opinion of different technical experts and a transcript of their cross-examination in a UK court case). See also T 335/15, in which two months before the oral proceedings the opponent had filed a request that a technical expert be heard but did not specify on what point that expert would be speaking until the oral proceedings. The board ruled on the issue with reference to the findings in G 4/95 on oral submissions by an accompanying person. More generally, this issue is discussed in chapter III.V "Representation".