Where the composition of an opposition division is in breach of Art. 19(2) EPC, this is deemed to be a substantial procedural violation that can warrant reimbursement of the appeal fee and remittal of the case (established case law, see T 251/88, T 939/91, T 382/92, T 476/95, T 838/02, T 825/08, T 1349/10, T 1700/10 T 135/12, T 285/11).
In T 838/02 the chairman of the opposition division ought to have been excluded as he had participated in the grant proceedings, yet he had been in place when the patent was revoked. The board held that it was immaterial for the purposes of Art. 19(2) EPC 1973 whether or not the opposition division had actually been aware of the circumstances justifying exclusion. If the composition of the opposition division was contrary to Art. 19(2) EPC 1973, the parties should be given the opportunity to comment before the board decided on the remittal of the case.
Although the facts in T 1349/10 were similar, the board distinguished the situation from that in T 838/02, as the patent had been maintained in the opposition proceedings, which meant that the public too was affected by the procedurally flawed decision. The board held that violations of Art. 19(2) EPC 1973 should lead to a remittal regardless of the parties' position at least in situations where third parties were affected by the outcome of the defective first-instance proceedings.
In T 234/11 the dossier showed that two members of the opposition division had taken part in the grant proceedings. The board ruled that the wording of Art. 19(2) EPC left no room for discretion. Nor did the conclusion reached in T 838/02 apply because here the issue was the patent's maintenance in amended form and, besides, the parties to the proceedings had conflicting interests: one sought remittal to the opposition division; the others did not want that.