According to the practice of the boards of appeal, affidavits or statutory declarations, whether in original or copy form, are considered as possible means of providing evidence. One purpose of written declarations is to avoid the need to hear the undersigning person as a witness. Where such declarations consist of answers to questions put forward by legal experts several declarations may have certain stereotyped formulations in common. The board is not obliged to check the signatures as long as no counter-opinion has been presented concerning those signatures (T 674/91; see also T 558/95).

In T 474/04 (OJ 2006, 129), where one party invoked T 674/91 to justify not having to hear the author of an unsworn witness declaration ("eidesstattliche Versicherung") as a witness, the board pointed out that the case before it was different in that the fundamental assertions made in the declaration were contested, the author had been offered as a witness, and the appellant had consistently demanded that he be heard. The opposition division's decision not to summon him as a witness although he was available had handicapped the appellant in its defence against what turned out to be the decisive piece of evidence. It was observed that this piece of evidence largely lay "within the power and knowledge of the opponent".