In T 361/00, as to the two statutory declarations (relating to visits to a cement works), the board had no doubt that they had been made in good faith but found them to be contradictory. Having found that the appellant's (opponent's) submissions at the oral proceedings had not clarified the contradictions, it concluded that the appellant had failed to furnish conclusive proof of the alleged prior use. Lastly, it held that there was no need to hear the witness, giving reasons for this finding (on contradictory statements, see also T 833/99 and T 832/13, serious doubts due to the general nature of the statement).
In T 1266/16 the board stated that, notwithstanding that the two declarations submitted were "word-for-word identical", they did not contain any specific detail with respect to the suppliers they referred to, let alone any data regarding purchase or analysis performed. As such, these statements, unsupported by any corroborating evidence, could not be considered as proof of the appellant's argument.
In T 1914/08 the board – like the opposition division at first instance – regarded two witnesses' testimonies as the decisive evidence proving without any gaps the alleged prior public use. Each testimony, considered in isolation, gave a consistent and full picture of the process in question.
In T 1293/13, to overcome an objection of insufficient disclosure based on a reference to a machine that was no longer in existence, the proprietor had submitted a statement from the president of the company that manufactured machines of this kind attesting that the results would be the same irrespective of the machine used. The board was not persuaded by the statement as it was not based on any verifiable data.
On an alleged prior use, the board in T 453/02, disagreeing with the patent proprietor (respondent), held the content of three statements to be consistent and convincing. Furthermore, the impartiality of the first statement could not be doubted as it had been made by the patent proprietor itself. In any event, the proprietor could not plausibly argue that the alleged public prior use had been based solely on testimony given after the date of filing of the contested European patent application. That testimony had been corroborated by other evidence (original trade fair catalogue bearing a date).
In T 1043/93 the deposition of the witnesses (who did not bring documents as requested by the board) contained unclear answers, inconsistencies, and were in conflict with another, so that the board found that the related alleged public prior use was not proven and could not be considered to belong to the prior art (Art. 54(2) EPC)
In T 100/97, without casting doubt on the good faith of the submitted declaration, the board stated that for the content of such statements to be considered sufficiently credible, it had to be corroborated by documents of a definite date. In the absence of any such documents, the board decided that it could not be established with a sufficient degree of certainty what had been made available to the public before the priority date of the opposed patent.
In T 473/93 the board decided that the appellant's surmise that he had been in error in making his statutory declaration was not sufficient to allow orally presented facts which deviated from the declaration to appear more credible. The fact alleged orally therefore had to be regarded as not proven.
An unsigned statement by an unknown and unnamed person should in principle be given minimal weight (T 750/94, OJ 1998, 32; T 1818/12). In T 212/97, the board could not regard the citation of facts based on hearsay and not accompanied by a witness testimony as adequate evidence for the alleged prior uses.