Amendments occasioned by national prior rights – which are not included in the grounds for opposition specified in Art. 100 EPC – are also admissible during opposition proceedings. The reference in R. 80 EPC to R. 138 EPC (former R. 87 EPC 1973), which as a general provision of the EPC 1973 also applies to opposition proceedings, makes this absolutely clear (see prior practice in T 550/88, OJ 1992, 117).

This was also confirmed by the board in T 15/01 (OJ 2006, 153). In that case, the appellant had justified the filing of separate claims for Spain and Greece on the grounds that a number of claims as granted might be ineffective in Spain and Greece, since the reservations made by both contracting states under former Art. 167(2)(a) EPC 1973 (now deleted) were still in force on the date of filing of the application. The board held that, although the EPC 1973 did not contain an explicit provision for the corresponding situation where an applicant or proprietor wished to take into account the reservation made by an EPC contracting state under Art. 167(2)(a) EPC 1973, it had been the established practice of the EPO from the very beginning to accept the filing of separate sets of claims for such contracting states. This practice had also been confirmed in G 7/93 (OJ 1994, 775), in which the Enlarged Board of Appeal regarded such situations as an exceptional case in which amendments might be appropriate at a very late stage of the examination procedure. The technical board further made it clear that the general purpose of R. 57a EPC 1973 (R. 80 EPC) was to allow amendments only where they were made to overcome an objection against the validity of the European patent. It followed from the reference to R. 87 EPC 1973 (R. 138 EPC) that, within the framework of the centralised opposition procedure before the EPO, amendments were also to be allowed where the patentee intended to overcome a possible ground of invalidity which only existed in respect of a particular contracting state. Thus, R. 57a EPC 1973 was not infringed by the formulation of a separate set of claims for a contracting state in which, due to a reservation made under Art. 167(2)(a) EPC 1973, certain product claims as granted would be considered invalid or ineffective.