In appeal proceedings, the case law recognises the right of all parties to be heard (see J 20/85, OJ 1987, 102; J 3/90, OJ 1991, 550; T 18/81, OJ 1985, 166; T 94/84, OJ 1986, 337; T 716/89, OJ 1992, 132), albeit within the limits of expediency (see T 295/87, OJ 1990, 470). The parties also have a right to oral proceedings.

Furthermore, G 1/86 (OJ 1987, 447) recognised the validity of the principle that all parties must be treated equally in similar legal situations in proceedings before the boards of appeal.

Decision T 73/88 (OJ 1992, 557) deduced from this that all parties to proceedings had the right to continue appeal proceedings. If there was already one valid appeal, no further appeals were needed and the fees paid for appeals filed later had to be refunded. However, in decision G 2/91 (OJ 1992, 206) the Enlarged Board disagreed. It took the view that from the legal point of view the status of parties who had filed an appeal was not comparable with that of those who had not. It was clear from generally recognised principles of procedural law that the appellant alone could decide whether the appeal filed by him was to stand. Art. 107, second sentence, EPC 1973 only guaranteed non-appellants who were party to proceedings of the first instance that they were parties to existing appeal proceedings. A person who was entitled to appeal but did not do so, settling instead for being "automatically" a party to the appeal proceedings, had no independent right of his own to continue those proceedings if the appellant withdrew his appeal. He acquired that right only by filing an appeal himself and paying the associated appeal fee. By the same token, there was also no reason to refund the fee for any appeals filed after the first, unless the requirements of R. 67 EPC 1973 were met. The related issue of whether non-appealing parties can file substantive requests is dealt with in G 9/92 date: 1994-07-14 and G 4/93 (both OJ 1994, 875; see also chapter V.A.3.1. "Binding effect of requests – no reformatio in peius").

In T 864/02, the board found that, according to some case law, a non-appealing party as of right did not have the same procedural status in all respects as did an appellant e.g., it did not have an independent right to continue appeal proceedings if the appellant withdrew its appeal (see G 2/91, OJ 1992, 206 and G 9/92 date: 1994-07-14, OJ 1994, 875). However, the case law also confirmed the right to be heard of all parties to pending proceedings (principle that all parties must be treated fairly and equally). The party as of right was thus entitled to raise a novelty objection where the notice of opposition had raised this ground and the submission therefore lay within the framework of the opposition procedure. In T 591/01 and T 475/97 the respective parties as of right were allowed to submit requests.