In any proceedings before, inter alia, an opposition division or a board of appeal, evidence may be given by producing documents, either in response to an order by the department hearing the case (Art. 117(1)(c) EPC) or – more commonly – on a party's own initiative in support of its claims. As the EPC neither defines the term "documents" nor gives any indication of the probative value of such documents, the principle of free evaluation of evidence applies. Any kind of document, regardless of its nature, is admissible during proceedings before the EPO, including appeal proceedings (T 482/89, OJ 1992, 646).

In T 1698/08 the respondent (patentee) objected to the admission of an (internet) extract from the Zürich Commercial Register as it stated at the end that the information was provided without warranty and had no legal effect whatsoever, which in its opinion had the consequence that the extract could not be considered as a means of evidence within the meaning of Art. 117(1) EPC. The board stated that a refusal to admit such a piece of evidence (an uncertified extract from a commercial register) could therefore not be based on Art. 117(1) EPC. The board decided that there was no reason to exercise its discretion to refuse to admit the evidence, as it could neither be said that it was irrelevant nor that it was unnecessary. A refusal to admit it could in any case not be based on statements in the document with respect to the accuracy of the facts it contained. Such statements relate to the probative value of a document.

In T 71/99 the minutes of the proceedings as taken by the opposition division did not provide a full account of the conduct of the oral proceedings. To show the board what had actually happened, the respondent submitted part of a copy of a report of the opposition proceedings which had been dictated by his representative in the course of those proceedings. The appellant argued that this document should not be admitted, albeit without disputing the facts set out in it. Since the submitted part of the report was significantly more precise and not difficult to understand, the board saw no reason to disregard the evidence. In R 3/08 the Enlarged Board, having taken private minutes into account, considered that there was no indication that the petitioner had raised any objection.

On minutes of oral proceedings as evidence of the course of the proceedings, see chapters III.C.7.10., V.B.3.6.4. and R 7/11. See also in this chapter: T 361/00 (minutes not contested), and T 2301/12, in which, the accuracy of the minutes of the oral proceedings having never been challenged, the board started from the position that they represented a faithful account of events. Similarly, the Enlarged Board in R 6/17 found that the petitioner had neither objected to nor requested a correction of the minutes. The minutes were to be considered a sound reproduction of the course of the oral proceedings before the board.

In various cases concerning prior use, photographs were submitted as evidence. In T 833/99 the photos filed as evidence were considered too unclear; in T 973/10, the late-filed photos were not admitted, because their probative value was found to be insufficient following an examination of their prima facie relevance. In T 1410/14, which concerned a device for connecting the wagons of a train that had been tested on a stretch of railway track, the opponent produced photos showing a passenger footbridge spanning the track from which an onlooker could see the transversal movement between the two wagons as evidence that photos or video equipment could have been used to record the lateral movement and that the feature at issue had thus been disclosed. In T 564/12 and T 453/02, the photos were filed as annexes to affidavits. In T 1647/15, the patent proprietor hinted as regards the photographs that the trailers might have been modified since the priority date of the patent; however, taking common sense in particular into account, the board decided that this was very unlikely and that a person skilled in the art could easily detect any inconsistencies between the original technical drawings and the photographs (see also e.g. T 1127/97, T 544/14).

T 523/14 concerned an advertising newsletter as an alleged prior publication. Of the evidence produced by the opponents, the appellant (patent proprietor) argued that D61 – a screenshot of Microsoft Outlook documenting the forwarding of the e-mail – might be a forged document. However, the appellant did not indicate, and the board could not find, any inconsistency or discrepancy in D61 which could suggest that this document was a forgery. The mere fact that it was a screenshot of Microsoft Outlook was insufficient to warrant the conclusion that it had been forged.

Where there is no evidence of forgery, it is not necessary to submit the originals of instruments of transfer. Failure to submit originals is not sufficient by itself to raise reasonable doubt as to the validity of the transfer (T 2466/13, which concerned a transfer of priority right).

In T 518/10 (concerning a transfer of opponent status), opponent 2 had filed a copy of an extract from the Norwegian companies register from which it was clear that its name had changed following a merger. The board considered this evidence sufficient to demonstrate who was opponent 2's universal successor in law.

In T 301/94 a report by a "huissier de justice" (court bailiff) concerning champagne bottles had been submitted as evidence of alleged prior use. The evidential value of such official reports drawn up by a "huissier de justice" was no longer questioned at the appeal stage (see also T 838/92).

In T 801/98 lock designs had been deposited, under seal, with a court bailiff.

In T 1464/05 details of the composition of a product cited in support of alleged prior use (sale for testing) had been deposited with a notary (as a non-public document).

In T 1332/12 the respondent (opponent) filed a copy of Japanese application D7 as evidence of the prior art and a JPO machine translation into English (D7T). The appellant (patent proprietor) filed later D7JPO, in its view a more accurate machine translation of D7. The board pointed out that there was nothing in the EPC to prevent a party from filing a corrected translation of a document filed as evidence, even if the evidence and/or translation was filed by the other party to the proceedings. This also applied if the document was a patent application. See chapter III.F.5. "Translations".

For internet publications, see in particular T 286/10 and T 2227/11, reported in this chapter.