In case T 2534/10 the chairman of the opposition division had proposed, late in the evening of the only scheduled hearing date, that the oral proceedings be continued the next day. Although the patent proprietor had objected to this proposal, the proceedings had been continued the next day, and both parties had attended. The board observed that the two months' notice to be given in summons to oral proceedings under R. 115 EPC met the parties' fundamental need to be able to plan for and estimate the likely course of those proceedings. They had the same need when it came to continuing proceedings on a calendar day other than that specified in the summons. Accordingly, a fresh summons had to be issued if proceedings were to be continued beyond the calendar day specified in the original summons.

In T 1674/12 the opposition division had continued the oral proceedings on 9 September 2011, even though the summons was only for 8 September and two opponents had objected. The board held that, in the light of T 2534/10, the opposition division had committed a procedural error, irrespective of the opponents' objections: to continue the proceedings on 9 September, it had to have the express consent of all parties. T 2534/10 had also ruled that remittal was necessary only if the error had affected the final decision; a case could be remitted only to recommence procedural acts performed on the second day, not covered by the summons. In the case in hand, the proceedings would have taken essentially the same course, even if the division had adjourned the oral proceedings on the evening of 8 September rather than continuing them the following day.