Evidence must be taken as soon as a dispute arises (J 20/85, OJ 1987, 102). Evidence may also be taken from parties without the presence of their patent attorneys if the latter have been informed of the hearing (see T 451/89 and T 883/90). When a party seeks to prove potentially relevant facts by means of the statement of a witness, it is particularly important that this statement be furnished early in the opposition phase so as to enable the witness to give oral evidence in accordance with Art. 117 EPC 1973 (T 953/90).
In T 1096/08, the board could not share the view of the opposition division that the alleged prior use had been proved to the requisite standard. Exercising its discretion under Art. 12(4) and 13(1) RPBA, the board considered it appropriate to take evidence from the two witnesses offered by the respondent/opponent during the first oral proceedings. By contrast, the board did not admit to the first oral proceedings a further witness who had been offered at a late stage, namely with the respondent's reply to the grounds of appeal, and without any further substantiated facts or arguments as to the potential relevance of the witness testimony during these proceedings. Again, applying the required strict standards with regard to the admissibility of late-filed evidence of public prior use, the board refused to take evidence from a fourth witness offered shortly before the second oral proceedings (approximately a year later), since the respondent had failed to provide any clear explanation or sound reasons as to why the allegation of public prior use could not have been made any earlier. In the board's view, the piecemeal approach of the respondent to asserting yet another alleged prior use shortly before the second oral proceedings clearly could not have been dealt with by the appellant or the board without further adjournment of the oral proceedings.
In T 753/09 an expert declaration had been filed by the appellant/opponent as a response to the summons to oral proceedings issued by the board, ostensibly for demonstrating how the skilled person would interpret documents E1 and E2. The expert declaration had been submitted less than two months before the oral proceedings and was therefore regarded as late submission. The board stated that it would allow such belated evidence only if it were sufficiently relevant and if the other party could reasonably react to the late filing. In the case at issue, the expert opinion failed to fulfil those requirements:
Firstly, the declaration did not provide more technical information than the documents E1 and E2 themselves, thus from a technical point of view it was not more relevant than the documents on file. In principle, it was the primary and everyday task of a board of appeal under the EPC, comprising at least two technically qualified members to establish what various technical documents taught to the skilled person. Given that the technical teaching of both documents was relatively simple, and given that patent attorneys normally had a technical background themselves, the expert opinion might as well be put forward in an equally convincing fashion by the authorised representatives of the appellants, with no less evidential weight before the board. Secondly, the respondent/proprietor had various options to deal with such late filed evidence, since an expert declaration had to be considered not just as an argument, but evidence pursuant to Art. 117(1)(e) EPC. It was certainly open to the other party to contest the qualifications of the expert (which the respondent did). More importantly, if the above declaration requires expert knowledge thereby acquiring greater evidential weight than "simple" statements, then the other party had to be given the possibility to have such an expert declaration verified or possibly refuted by another expert with the same qualifications (as also requested by the respondent as an auxiliary measure). Indeed, in the particular case, such a defence against the expert declaration required quite some time and the present circumstances did not allow enough time for the respondent to prepare a suitable counterstatement, also given the holiday season between the submission and the oral proceedings.
With regard to the consideration of late-filed evidence see also Chapter IV.C.1, "Late submission".