In T 390/86 (OJ 1989, 30) all three members of the opposition division were changed between the oral and written decision. The board held that a decision must at least be written on behalf of and represent the views of the members appointed to decide the proceedings, and must bear signatures which indicate this. 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 have taken place. 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 of appeal developed the principles established in T 390/86, further holding that even though only one member of the opposition division had been replaced after the oral proceedings, there was no longer any guarantee that the reasoned decision signed subsequently accurately reflected the point of view of all three members who had taken part in the oral proceedings. The situation in which one of the appointed members was incapacitated (e.g. through illness) was quite different; in such cases one of them could sign on behalf of the member unable to do so after checking that the reasoned written decision represented the point of view of all the members who had taken part in the oral proceedings. This was followed in other cases where only one member of the opposition division had changed between the oral and written decision; see e.g. T 960/94 and T 862/98. However, where the change in the composition of the opposition division occurs prior to the oral proceedings, this is not by itself a breach of the right to a fair hearing (T 1652/08). In the case at issue the opposition division had at all times been properly composed and, accordingly, there had been no infringement of Art. 19(2) EPC 1973.
In T 900/02 a number of procedural irregularities had occurred after the oral proceedings before the opposition division, including a delay of over three years before despatch of the written decision (in fact, two decisions were issued, in different compositions). The board followed T 390/86 and T 862/98; a signed written decision issued after oral proceedings should be the decision of those members of the first instance who conducted the oral proceedings and none others. If for any reason, (even quite acceptable and understandable reasons such as illness or retirement), the same three members were not available, then the parties were to be offered new oral proceedings.