c) Events long past 

In T 1191/97 the appellant's criticism of the evaluation of evidence by the department of first instance did not pose a serious threat to the witness's credibility. The fact that the events at issue had taken place a long time ago could readily explain certain imprecisions in the witness's testimony. The board saw no indication that the witness had been in breach of his obligation to testify to the best of his recollection.

In T 61/07 the board made clear that the doubts cast by the respondent on the witness's memory about events which had happened 23 years ago 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.

In the circumstances of case T 918/11, the board considered that the reasoning of the impugned decision that "... the mere declaration of one witness in connection with facts which occurred between 1992 and 1997, i.e. at least 14 years ago, is not sufficient to prove the details of prior use" was not well founded.

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 1604/22, in the board’s view, D6a and D6d were affidavits, i.e. statements sworn under oath, which should be given a high probative value, unless other evidence casts doubt on them. The fact that the affidavits might have been written by someone else, e.g. the respondent's representative, was immaterial since by signing them the authors endorsed the statements made in the affidavits. The board was satisfied that this evidence was therefore sufficient and the alleged inconsistencies and doubts raised by the appellant were not convincing. The fact that the events in question took place a long time ago could easily explain some imprecisions in the witnesses' testimonies, without calling into question the overall credibility of their statements. The appellants also did not explicitly question the witnesses' credibility.

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 untrue statements. A person can be honestly mistaken in his recollection of an event, particularly if the event took place sometime previously.

In T 2217/19, with regard to novelty, the appellant (opponent) submitted HE2, a statement by an inventor of HE1 (European patent) made 25 years after the priority date of HE1. The board agreed that the time passed might be a relevant criterion for the evaluation of the credibility and the precision of said declaration, even if made in good faith. The board considered that the mere recollection of the values (without written evidence) was not sufficient as clear and unambiguous proof that the compositions of HE1 and in particular the one of its example 1 were characterised by the features (i) and (ii) as defined in claim 1. Even assuming that the recollections were based on archival documents, it would at least have been necessary to state this fact in the declaration by explaining the nature of the respective documents. In the absence of such an explanation about the source of the data indicated in the declaration and in the absence of any supportive evidence, they could not be considered as sufficiently proven. This conclusion was reached after also taking into account the fact that the value reported (for the gel content) was at the upper limit of the range recited in claim 1. Thus, even a small error in the recollection of this value could have the consequence that the gel content was within or outside the range defined in claim 1. The subject-matter of claim 1 was novel over HE1.

In T 2517/22 the opposition division did not take into account the offer to hear as a witness the undersigned of the affidavit D2a on the issue whether or not D2 was part of the prior art. Instead of accepting the evidence offered, the opposition division appeared to have based its decision on general assumptions made on the capability of persons to recollect events after a certain time period (15 years). By making such assumptions without hearing the offered witness, the opposition division had in fact assessed evidence without examining it. A sufficiently exact recollection of various events 15 years later should not have been denied beforehand. (See also this decision under present chapter III.G.3.3.4 "Improper reasons for rejection of evidence offered").

In T 483/17 (prior use – up to the hilt) the respondent (patent proprietor) doubted that the witness had been able, in his declaration on oath, to reproduce all the details about the delivery, which had taken place more than 10 years earlier, and pointed out that the appellant, who had obviously pre-drafted this declaration, must have had more information and documents than it was willing to submit in these proceedings. However, since the declaration was not needed to convince the board of the delivery, any "inconsistency" in it was irrelevant.

T 2165/18 (see also the abstract below, under chapter III.G.4.3.4c) "Archives and internet publications") turned on an undated user manual that had been published online. The board ultimately found that the statements made by a witness were not enough on their own to fill in the gaps in the evidence as to its date of publication and the software version it had been supplied with. It was unlikely that a witness, even if the manual's author, would still be able to remember the whole text nine years later. The opponent cited the decisions in T 1798/14, T 2565/11 and T 918/11 in support of its contention that a single witness's testimony could in fact be enough to prove prior use and that a witness could also fill in gaps in the alleged facts, but the board rejected this position, ruling that they did not apply in the evidential situation in the case in hand. See also T 939/14 below.