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 (see also T 243/87, T 960/94 and T 2076/11).
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, T 862/98, T 2175/16 and T 2348/19.
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 and held that 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.