4.4.1 General

Because Art. 115 EPC sets no upper time limit for presenting third-party observations, in principle they can also be filed after expiry of the opposition period, and so even during inter partes appeal proceedings. Although the Art. 114(2) EPC provision on late-filed submissions mentions only the parties to the proceedings, established case law holds that submissions (i.e. facts and evidence) emerging from third-party observations not filed until after expiry of the opposition period are likewise to be treated, by way of a legal fiction, as "late". This means that Art. 115 EPC cannot serve to extend third parties' rights, let alone extend them beyond the rights of parties to the proceedings. In other words, where third-party observations are filed after the time limit under Art. 99(1) EPC, the principle enshrined in Art. 114(1) EPC of examination by the EPO of its own motion is to be applied on the fictional basis that those observations are late, i.e. they are subject to the criteria developed in the case law for the board's exercise of discretion in deciding whether to admit late-filed submissions within the meaning of Art. 114(2) EPC. (T 1756/11, see also T 402/12, T 1216/12, T 1528/13, T 1285/15).

Since the RPBA specify some criteria for exercising this discretion in appeal proceedings with respect to the submissions of the parties to the proceedings, these criteria must also apply to third-party observations. Hence, the criteria laid down in Art. 12(2) RPBA 2020 and Art. 12(4) RPBA 2007 are to be taken into consideration in deciding whether and to what extent the submissions at issue must be considered (T 2255/15).

Irrespective of a third party's legal status, the principle that the EPO must examine the facts of its own motion in first-instance administrative proceedings does not have the same legal importance in judicial appeal proceedings, in particular in inter partes proceedings (G 9/91 and G 10/91, OJ 1993, 408, 420).

In T 1756/11 the board observed that the opposition divisions should at least comment on the relevance of third-party observations, for example in the summons to oral proceedings.

In T 301/95 of 28 March 2000 date: 2000-03-28, a third party had alleged public prior use after expiry of the period for opposition, i.e. belatedly. Under Art. 114(2) EPC 1973, it was at the discretion of the opposition division and the board of appeal whether or not to consider the belated submissions, but in deciding whether to do so, the most important criterion was the relevance of the belatedly cited prior art. The observations were not considered.

According to T 923/10 the boards have discretion to take such observations into consideration or to disregard them. When exercising their discretion the boards normally take criteria into account which they consider when they decide about the admissibility of submissions by parties to the proceedings that are considered "late-filed" in view of Art. 114(2) EPC and Art. 12(1) RPBA 2007, Art. 12(2) RPBA 2007, Art. 12(4) RPBA 2007 and Art. 13(1) RPBA 2007, and Art. 13(3) RPBA 2007. These criteria include the relevance of the submissions filed (see for example T 1137/98, T 390/07, T 544/12). More specifically, it is the boards' established case law that a crucial factor is whether submissions filed late in appeal proceedings are prima facie highly relevant, i.e. likely to change the outcome of the proceedings (T 1216/12). In T 1348/11 the board added that submissions provided by a third party should not be given a more favourable status than submissions of a party to the proceedings to whom Art. 114(2) EPC applies.

In T 1756/11 the board observed that the boards usually have to disregard late-filed third-party observations in opposition appeal proceedings of their own motion, unless they relate to amendments to the claims or other parts of the patent made during the opposition or appeal proceedings.