The wording of Article 24 EPC and procedural considerations
imply that an objection to the members of a Board of Appeal can
only be made in the course of an appeal pending before that
Board of Appeal.
Article 23(3) EPC states that "Members" of a Board of Appeal may
be objected to by any party. This implies that objection may be
made against each or all the members of that Board.
The Boards of Appeal are the final instance and their decisions
become final once they have been delivered, with the effect that
the appeal proceedings are terminated. In proceedings,
partiality would be to willingly favour the party by granting it
rights to which it is not entitled or by intentionally
disregarding the rights of another party. After the decision has
been taken a Board is no longer empowered or competent to take
any further action apart from drafting the written decision
(apart also Rule 88 EPC). Any further action which in the light
of the decision becomes necessary, is the responsibility of the
internal administration.