c) Prima facie relevance of late-filed objections and evidence 

Prima facie relevance is a recognised criterion for assessing the admissibility of late-filed objections in first instance opposition proceedings (see e.g. T 2883/19). In numerous decisions the boards held that the opposition division applying the prima facie relevance criterion had relied on the right principles and, in the case in hand, had applied them in a reasonable way (see e.g. T 3166/19, T 415/20, T 687/20, T 803/21, T 214/20).

T 1161/20 illustrates the importance of giving reasons as to why the opposition division's decision not to admit objections was incorrect.

(i) Party’s disagreement with the result of the substantive assessment – not sufficient to demonstrate an error in the use of discretion

The mere disagreement by the party with the result of the substantive assessment by the opposition division is not sufficient to indicate an error in the use of the discretion. This was, for instance, underlined in T 2883/19. In the same decision, the board also pointed out that it was not apparent that the prima facie relevance evaluation of the added-matter objection at issue was based on manifestly incorrect technical assumptions. The board exercised its discretion under Art. 12(6) RPBA 2020 not to admit this objection into the appeal proceedings.

Similarly, in T 61/21 the board did not accept the appellant’s (opponent’s) arguments according to which the opposition division, when deciding not to admit D10 as prima facie not relevant, had incorrectly placed excessive emphasis on the supposed remoteness of the document. In the board’s view, these arguments addressed why the opposition division, according to the appellant, should have found document D10 prima facie relevant, rather than demonstrating that the opposition division had followed incorrect principles or used its discretion unreasonably.

In T 307/22, however, the board reviewed the substantive basis (valid claim of priority) for a decision of the opposition division not to admit a citation. In the board's opinion, the opposition division had failed to recognise that the claimed invention had only partial priority. The board therefore exercised its own discretion. However, it too decided not to admit the citation in question (D7), on the basis that it lacked relevance for novelty. Its relevance for inventive step had been asserted by the appellant for the first time at the oral proceedings. The board decided under Art. 13(1) and (2) RPBA 2020 not to admit its submissions on this, finding that D7 was not prima facie relevant to the inventive step of the alternatives with a later effective date.(ii) Aspect that was not submitted in the first-instance proceedings disregarded – no error of discretion

(ii) Criterion "prima facie not more relevant than other documents on file" incorrectly applied

In T 435/20 the board observed that the opposition division was mistaken in holding that the declaration of a technical expert filed together with supporting documents (D81 to D90) on the one hand and the representative’s arguments on the other hand were equivalent and that this could justify non-admittance of the declaration and the supporting documents. As pointed out by the board, arguments submitted by a party's professional representative do not qualify as means of giving evidence under Art. 117(1) EPC and may therefore have a different weight depending on whether or not they are supported by further evidence.

(iii) Insufficiently reasoned discretionary decision – error in the use of discretion

In T 2055/20 auxiliary request 1 filed during the oral proceedings before the opposition division was not admitted because, in the opposition division’s view, it did not prima facie overcome the lack of inventive step objection raised against the main request. However, the board found that the opposition division had provided in the written decision only an unreasoned statement for the non-admittance of this request . In particular, no reasoning was provided as to why this request, prima facie, did not overcome this objection. Moreover, according to the minutes of the oral proceedings before the opposition division, when dealing with the admittance of said request, only issues of added subject-matter were raised and discussed with the parties. The board concluded that the opposition division’s decision resulted from an error in the use of discretion and admitted the request into the proceedings.

In T 1657/20, the board was not convinced that the opposition division's use of discretion in its decision not to admit based on a lack of prima facie relevance was correct. Citation A8 had been filed late in the opposition proceedings, and the opposition division did not admit it into the proceedings for lack of prima facie relevance. In the board's view, however, the facts on which the opposition division had based its discretionary decision were not entirely apparent from the contested decision. In particular, the opposition division had substantiated the lack of prima facie relevance only in relation to claim 1 of the main request but not the broader claim 15. It was also debatable how rigorously the opposition division had assessed prima facie relevance for inventive step. Therefore, the board exercised its own discretion and admitted A8 into the appeal proceedings under Art. 12(4) and (6) RPBA 2020.