The question of law referred to the Enlarged Board of Appeal in G 9/92 date: 1994-07-14 and G 4/93 (both OJ 1994, 875) asked whether and to what extent a board of appeal could depart from the request formulated in the notice of appeal when deciding opposition appeal proceedings, to the disadvantage of the appellant.

The Enlarged Board took several factors into account. The aim of the appeal was to eliminate an 'adverse effect'. As the filing of an appeal was subject to a time limit, it would not be consistent to allow non-appealing parties the unrestricted right to alter the extent of the proceedings by submitting their own requests without limitation of time. A non-appealing party as a respondent had the opportunity to make what it considered to be appropriate and necessary submissions in the appeal proceedings to defend the result obtained before the department of first instance.

The Enlarged Board thus concluded that:

1. If the patentee was sole appellant against an interlocutory decision maintaining his patent in amended form, neither the board of appeal nor the non-appealing opponent (as party to the proceedings as of right under Art. 107, second sentence, EPC 1973) could challenge maintenance of the patent as thus amended.

2. If the opponent was sole appellant against an interlocutory decision by an opposition division maintaining the patent in amended form, the patentee was primarily restricted in the appeal proceedings to defending the patent as thus maintained. Amendments proposed by the patentee (as party to the proceedings as of right under Art. 107 EPC 1973, second sentence) could be rejected by the board as inadmissible if they were neither appropriate nor necessary (see e.g. T 321/93).

As legal uncertainty had been created by the fact that the case law of the boards of appeal had not been uniform as regards the principle of prohibition of reformatio in peius when applying or interpreting decision G 9/92 date: 1994-07-14 (OJ 1994, 875), a further question was referred to the Enlarged Board, which was answered in G 1/99 (OJ 2001, 381). See in this chapter V.A.3.1.8.