a) When decision is announced in oral proceedings 

The written reasons for a decision delivered during oral proceedings can only be signed by members of the deciding body who took part in the oral proceedings. The same principle applies if between the orally delivered decision and the written decision proceedings in accordance with R. 58(4) EPC 1973 (R. 82(1) EPC) have taken place (T 390/86, OJ 1989, 30). In T 390/86 the board also stated that in a case where a final substantive decision has been given orally by an opposition division during oral proceedings, if the subsequent written decision giving the reasons for such oral substantive decision is signed by persons who did not constitute the opposition division during the oral proceedings, the decision is invalid.

In T 243/87 the board declared a decision to be null and void where one of the three signatures was provided by a member who had not attended the oral proceedings.