3.2.10 Parties treated equally (or not)

In case T 712/97 the opposition division did not allow the appellant's experimental report in response to the respondent-patentee's experimental report into the proceedings. To admit the experimental report of one party, but not the response of the other party gave the appearance of discriminatory treatment. The opposition division had committed a procedural violation.

The board in T 523/14 considered that it was contrary to the principles of procedural fairness and of equal treatment of the parties to admit late-filed D55 (written statement submitted by the opponent), while disregarding late-filed D54 (results of a search with internet wayback machine submitted two days later by the patent proprietor) because it lacked prima facie relevance for establishing the publication date of D11. In the board's opinion, D54 could serve to cast reasonable doubt on opponent's allegation that D11 was available on the Glasstech website in November 2007 or before and could thus have been admitted. However, in light of the opposition division's detailed consideration of D54, the board tended to conclude that its admission would not have altered the outcome. Nevertheless, in view of its potential impact on the most contentious issue in the proceedings, namely the public availability of D11, the board decided to consider D54 (see also T 1551/14).

In T 435/20 documents D81 to D90 were filed as a direct and immediate response to new evidence submitted by the appellant (patent proprietor) on the last day for making written submissions under R. 116 EPC. In admitting the late-filed documents D80 and its supporting documents D64 to D79 into the proceedings but not admitting documents D81 to D90 filed by the respondents in direct response, the opposition division had not respected the principles of procedural fairness and of equal treatment of parties. The fact that the opposition division's preliminary opinion was negative for the appellant but positive for the respondents could not justify a different treatment of the parties, since a preliminary opinion was neither binding nor definitive.