In G 5/91 (OJ 1992, 617) the Enlarged Board of Appeal stated that, although Art. 24(3) EPC 1973 was only applicable to appeal proceedings, an objection on the ground of suspected partiality could also be disregarded at first instance if it had not been raised immediately after the party had become aware of the reason for the objection (or if it was based on nationality). The system might otherwise be open to abuse.
In T 568/17 the board, with reference to G 1/91, held that if the appellant in the case in hand had wished to challenge the composition of the examining division because of the examiner's earlier actions during the international phase, it should have done so in the European regional phase when it became aware of that composition.
In T 49/11 after having received the summons which had made the parties aware of the composition of the board, the respondent filed two letters with the board before raising the partiality objection. In the first letter, the respondent had expressed its intention to speak German at the oral proceedings. The board held that such a statement constituted a procedural step within the meaning of Art. 24(3), second sentence, EPC, because it was a formal notification under R. 4(1) EPC. The partiality objection was therefore rejected as inadmissible. After analysing the text of Art. 24(3), second sentence, EPC in the three official languages (Art. 177(1) EPC), the difference between Art. 24 EPC 2000 and Art. 24 EPC 1973, and the transitional provisions of the EPC 2000, the board stated that it would have come to the same result under the old and the new text of Art. 24(3) EPC.
In T 1677/11 the board noted that the respondents had been aware of the closely related parallel appeal T 1760/11 of 16 November 2012 date: 2012-11-16, which had been decided by a board in an identical composition one week previously, right from the beginning of the current appeal proceedings. Nevertheless, it was only after an adverse decision in that case had been announced that the respondents raised their objections of suspected partiality in the case at issue. The board stated that regardless of whether the respondents had taken a specific procedural step in the current appeal proceedings, they had not submitted their objection immediately after having become aware of the reasons. It held that, in view of the fact that the objections raised were linked to both appeals, attendance at oral proceedings in T 1760/11 date: 2012-11-16 had to be regarded, in the factual context of the case now at issue, as a procedural step within the meaning of Art. 24(3) EPC. Thus, the objections under Art. 24(3) EPC were rejected as inadmissible.
In T 49/15 respondent 4 argued that the board's decision to admit the appellant's new main request had been a prerequisite for its partiality objection because it had only been then that the appellant had been favoured. The board rejected this argument: a party did not have to be adversely affected by a board decision before it could cite suspected partiality as a reason for objection.
In G 1/21 of 28 May 2021 date: 2021-05-28 the Enlarged Board considered that the appellant's third objection was filed inadmissibly late. The appellant had argued that because it was held in the first interlocutory decision that the Chairman of the Enlarged Board and a further member could be suspected of partiality, the members that participated in the panel with them would be "infected" by their biased views on the referral and therefore the suspicion of partiality also applied to them. The Enlarged Board stated that the risk of "infection" existed mainly before the filing of the first objection and the objection based on this circumstance could and should thus have been filed at that time. It was not credible that the risk of influencing other members only became a concern after the Enlarged Board had agreed with the appellant that its objection against the Chairman was justified. The Enlarged Board likewise held that Objections 2 and 4 were filed inadmissibly late. Both objections were based on circumstances that were known from the very start of the referral proceedings, and therefore could and should have been filed already at the time of filing the first objection at the latest.