f) Principles of fairness and equal treatment of parties 

In T 726/20 the board rejected the appellant’s argument that the discretionary decision of the opposition division not to admit auxiliary request 1, filed during the oral proceedings, had suffered from an error. The opposition division had not admitted this request because it was late-filed and based on subject-matter not previously covered by the claims. In the board’s view, these reasons were in line with the case law (see Case Law of the Boards of Appeal, 10th ed., IV.C. 5.1.4, in particular T 2415/13), which confirmed that claims can be amended during oral proceedings only in a manner that the opponent could be expected to deal with during the oral proceedings. This had the purpose of enabling all parties and the opposition division to prepare the case adequately, and of ensuring procedural fairness and efficiency.

In T 1617/20 the board held that it resulted in an inconsistent approach to base the decision on admittance of auxiliary requests 1 and 2, both filed at the oral proceedings before the opposition division, on different criteria. Moreover, using the prima facie allowability criterion to object for the first time at oral proceedings to a feature of the late-filed claim request that was already present in higher-ranking claim requests and had never been objected to before went against the principles of fairness and good faith. For these reasons, the board decided to overturn the opposition division's decision on the non-admittance (Art. 12(6) RPBA 2020).

In T 435/20 the board pointed out that in admitting the late-filed documents D64 to D80, including new evidence, into the proceedings but not admitting documents D81 to D90 filed in direct response, the opposition division had not respected the principles of procedural fairness and of equal treatment of the parties. The board also noted that the mere fact that the opposition division's preliminary opinion was positive for one party could not in itself justify not admitting any further documents by this party which were filed by the final date set by the opposition division for making written submission under R. 116(1) EPC.