2.3. Freedom of choice when selecting evidence

In accordance with the principle of free evaluation of evidence, any kind of evidence, regardless of its nature, is admissible (see T 482/89 and T 558/95). Under Art. 117(1) EPC, parties are free to choose what kind of evidence they present. In particular, they can make use of any of the means of evidence listed in that article (see T 543/95 and T 142/97, OJ 2000, 358); principle summarised in G 2/21 (OJ 2023, A85), point 40 of the Reasons – in relation with the right to be heard and that a decision should discuss the facts, evidence and arguments which are essential to the decision in detail (point 41 of the Reasons).

In T 1710/12, in the board's view, Art. 117(1) EPC gives no order of preference regarding the means of giving or obtaining evidence in proceedings before the EPO and it remains the free choice of a party to rely on the hearing of a witness (Art. 117(1)(d) EPC) or on production of a sworn statement in writing (Art. 117(1)(g) EPC). For other findings that witness testimony does not necessarily carry less weight than documentary evidence, see also T 918/11, T 2565/11 and T 441/04 (in which, however, the board first observed that documentary evidence was generally preferable to witness testimony for proving long-ago events).

Contrary to the appellant’s (patent proprietor’s) allegation, the board in T 1138/20 stated that the standard "beyond reasonable doubt", or for that matter any other standard, did not necessarily require a party to submit all documents at its disposal; it did not even necessarily require that a party submit documentary evidence at all. The evidence a party choses to adduce was at its discretion. That no documentary evidence was on file for a specific allegation of fact did not, as such, demonstrate an error in the finding of that fact. The appellant had to rather show, for example, that there was no evidence on file corroborating the finding of fact made by the opposition division. (points 1.3.4(a), (b) of the Reasons).

In T 329/02 the board found that it was not in keeping with good procedural practice for an opposition division not to take up an opportunity to hear a witness in evidence on a disputed matter that was highly relevant to the legal validity of the contested patent, and instead to require written declarations in place of the oral evidence.

See also chapter III.G.3.3 "Right to be heard" below.