In J 10/04 the Receiving Section had questioned the credibility of a sworn statement. Considering the sworn statement to have been based on personal impressions which were subjective and not always reliable particularly regarding a routine task, the Receiving Section had not invited the witness in order to hear her personally. The Legal Board did not share that view and stated that the Receiving Section should have heard the witness personally in order to be able to evaluate her credibility. The board evaluated sworn statements as a form of evidence with a high probative value especially if they were given with the awareness that wilful false statements were punishable by a fine or imprisonment or both under the applicable law. Strong reasons were therefore necessary to disregard this kind of evidence. These reasons could be a set of circumstances which made the statement very unlikely, so that the credibility of the witness would become decisive.
With regard to the credibility of witnesses, the board observed in T 1210/05 that even a person who was not being dishonest might make untruthful statements. A person can be honestly mistaken in his recollection of an event, particularly if the event took place some time ago. In the case at issue, the board could not share the view of the opposition division that the witness's testimony had to be true as there was no evidence that she was lying.
In T 804/92 (OJ 1994, 862) the opposition division had, in a communication to the parties, suggested in detail the content of a statement under oath. Such a practice was firmly rejected by the board because it involved the risk of leading witnesses and could seriously undermine the probative value of such statements. This applied to departments at any instance in proceedings before the EPO.
In T 61/07 the board made clear that the doubts cast by the respondent on the witness's memory concerned not the witness's credibility but the credibility of the testimony. However, it saw no reason to doubt that his testimony was credible. Just because the witnesses had each independently met a third witness before being heard did not automatically mean that their recollections had been influenced. Shortly before a party alleges prior use, witnesses are normally sounded out about what they actually remember. Such a discussion with a potential witness did not automatically imply that during it the party or one of its staff had influenced what the party remembered. Quite possibly, it was a way of refreshing the memory. The board did not find it unusual that the witness was unable to remember a particular name, given that he was being asked about events which had happened 23 years ago. On the contrary, it would have been more suspicious had he demonstrated a selective memory enabling him to recall the tiniest details of the case.
In T 905/94, the board held that the fact that one witness had made his declaration three years earlier than other witnesses was not sufficient reason to make his testimony more credible.
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). 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.
The opponent having died, the board had to decide in T 74/00 whether the evidence had shown that an heir or heirs had succeeded to the right of the opponent to appeal or to the appeal itself. In the board's view, the best evidence which could be provided was evidence of the relevant law of succession (here, Japanese law) by way of legal opinion from a Japanese attorney-at-law; the mere filing of copies of a party's correspondence with his instructing Japanese attorneys could not serve as substitute.