In some cases, experimental data submitted shortly before the oral proceedings before the boards of appeal was found to be late filed and so inadmissible under Art. 114(2) EPC. The reason invoked was that the handling of such data was more cumbersome and time-consuming than that of scientific publications, since it usually called for counter-experiments (T 342/98, T 120/00, T 157/03, T 311/10). In T 760/05 the board confirmed that filing an experimental report shortly before the date indicated by the board as the ultimate date for filing submissions ran counter to the principle that sufficient time should remain for the adversary to study it and perform counter-experiments. Similarly, in T 569/02, the board held that comparative experiments normally required careful consideration by the other party, including discussions with technical experts, who could not be expected to be immediately available. It might also be necessary for the other party to repeat the tests or perform other tests themselves. The board did not consider that the relevance of the tests played a role, since even relevant evidence of this type should not be filed at such a late stage in the proceedings.

Moreover, if oral proceedings have been arranged in inter partes proceedings, experiment results must be submitted sufficiently well in advance for the other party to have the opportunity to perform counter-experiments (e.g. T 270/90, OJ 1993, 725; T 939/90; T 375/91; T 685/91; T 305/94; T 245/10). Very late submission of experiment results (seven weeks before the oral proceedings) is contrary to a fair and expedient procedure (T 375/91, T 1008/05). In T 832/08, the board found that, where comparative experiments were submitted, the other parties had to be afforded sufficient time, so as not to breach their right to equal treatment.

In T 356/94 the board pointed out that taking into consideration comparative tests presented on the same day as oral proceedings were held could constitute an infringement of the other party's right to be heard, since the latter had had no material opportunity to check them (see also T 481/00, T 567/02).