No part of a patent's subject-matter (e.g. individual claims) not opposed within the nine-month time limit can be reviewed in either opposition or appeal proceedings. The opponent's statement under R. 76(2)(c) EPC (R. 55(c) EPC 1973) establishes the extent to which the patent is contested and thus the formal competence of the opposition division or board of appeal. The only exception to this principle concerns an opposition explicitly directed only to the subject-matter of an independent claim. In such a case, subject-matter covered by claims which depend on the independent claim can also be examined as to patentability (see e.g. G 9/91, OJ 1993, 408; see also T 323/94).

According to T 896/90, detailed grounds for opposition for a single granted independent claim do not mean that only that part of the patent is being contested, if the opponent has indicated that he wants the whole patent revoked. However, in T 737/92 (in which only arguments against process claims and not against composition claims were submitted) the board found that an opposition was filed only to the extent that it was substantiated (see also T 318/01).

Where two opponents lodge appeals contesting different sets of claims and one subsequently withdraws its appeal, it becomes a party as of right under Art. 107 EPC 1973 and the other opponent becomes the sole appellant. The scope of the appeal is defined by the latter's request, which the non-appealing party may not exceed and which binds the board (T 233/93).

In T 653/02 it was held that a board has no competence to examine a newly formulated claim derived by combination of granted claim 1 with a sub-claim not being within the extent to which the patent had been opposed; this did not fall within the exception allowed by G 9/91 (OJ 1993, 408). In T 646/02 the board found that the case at issue differed from the facts before the board in T 653/02, in that the subject-matter not opposed was described in the patent and was part of the independent claim as granted but was not itself the subject-matter of a dependent claim of the patent as granted. Whether or not the board had competence to examine depended, however, only on whether the patent was clearly restricted to a subject-matter not covered by the notice of opposition. This was done in T 646/02 by restriction to the subject-matter of the deliberately excluded dependent claim and, in the case at issue, by restriction to deliberately excluded variants of the invention. The board held that the exception in G 9/91 was not therefore applicable in the case before it either, since it was applicable only to subject-matter implicitly covered by the notice of opposition and not to those explicitly excluded.

In line with G 9/91, a patent proprietor could, in appeal proceedings, amend an uncontested dependent claim in accordance with R. 57a EPC 1973 (T 711/04).

Although the appeal procedure is to be considered as a judicial procedure in accordance with G 9/91 (OJ 1993, 408), this does not mean that a board in examining an appeal within the framework of the legal grounds and facts submitted by the parties is limited to only considering passages in documents indicated and facts submitted by the parties. Examination of the appeal may raise further relevant questions within this framework and parties thus be invited to file observations. Moreover, where amendments of the claims were made during opposition proceedings, these are to be fully examined as to their compatibility with the requirements of the EPC (T 1355/04).