In T 261/88 of 16 February 1993 date: 1993-02-16 the board stated that disqualifying partiality presumes that there is a preconceived attitude on the part of a deciding person towards a party to the case. When considering an allegation of partiality (in this case mainly based on the fact that the examiner was a former employee of the opponent), regard must be had to the particular facts of the case (cf. G 5/91). That the examiner's views differed from those held by the party was not disqualifying in itself. The board held that disqualifying partiality was limited to situations where the opinion of a person responsible for taking decisions affecting the right of parties was swayed by his attitude towards a party.

In T 900/02 the board stated that a suspicion of partiality inevitably arose if a member of an opposition division, or any other first‑instance body, first solicited and then accepted employment with a firm in which a partner or other employee was conducting a case pending before that member. It stressed that, to be above all suspicion of partiality, every member had to avoid any such situation at any time during the proceedings. No-one could be seen as independent of both parties while in the employ of one of them. The board held that the second examiner's employment by the respondent's representative's firm was both a fundamental deficiency in the first instance proceedings under Art. 10 RPBA 1980 and a substantial procedural violation under R. 67 EPC 1973.

In T 792/12 the appellant contended that the board did not want to listen to his arguments and appeared to lack impartiality because it interrupted him on several occasions. The board rejected this contention and referred to Art. 15(4) RPBA 2007, according to which the chairman of the board presides over the oral proceedings and ensures their fair, orderly and efficient conduct. According to the board, a chairman may interject in a party's submissions to ensure that the proceedings are efficiently conducted, in particular to avoid a party repeating arguments. In the same way, a chairman, or indeed any member of the board, may interrupt to ask questions which are, for example, considered important for reaching a decision. The board held the appellant's insistence that the board should not make any interruption during its pleadings, which it considered to indicate a lack of impartiality, was a misconception of what constituted a fair hearing.

In T 1055/05 the board decided that the examining division's refusal to minute the submissions of a party's representative during oral proceedings did not infringe the right to be heard or constitute grounds for suspecting partiality.

In T 710/15 the opposition division had rejected a new argument under Art. 114(2) EPC, which is only a basis for disregarding new facts or evidence. The board held that such an error of judgment did not prove the partiality of the chairman or the opposition division.