R. 43(2) EPC (R. 29(2) EPC 1973) provides that a European patent application may not contain more than one independent claim in the same category unless they involve (i) a plurality of interrelated products, (ii) different uses of a product or apparatus or (iii) alternative solutions to a particular problem, where it is inappropriate to cover these alternatives by a single claim.

The scope and potential applicability of R. 43(2) EPC in opposition proceedings was addressed in T 263/05 (OJ 2008, 329). Having considered the purpose and legislative history of the rule, the board concluded that it could not apply across the board to all amendments made during opposition proceedings. If it did, it would be impermissible to make any amendment introducing non-unitary claims, something which was not only permissible in opposition proceedings but also clearly appropriate given that the patent proprietor was no longer able to file a divisional application. To conclude that R. 43(2) EPC applied across the board in opposition proceedings would have watered down the decision in G 1/91 (OJ 1992, 253). R. 43(2) EPC could not be applied in opposition proceedings to prohibit the amendment of a patent as granted where it would be unreasonable to demand that the amended claims comply with it. This was the case where, otherwise, R. 43(2) EPC would force the patent proprietor to abandon potentially valid subject-matter already contained in the claims as granted. The board could not envisage any circumstances in opposition proceedings in which R. 43(2) EPC would be of any application because, once it had been established that an amendment to the claims was necessary and appropriate having regard to grounds for opposition, it would inevitably be unreasonable to impose the additional requirement that the amendment complied with the purely administrative provisions of R. 43(2) EPC.

In T 830/11 the board confirmed that the condition of conciseness of Art. 84 EPC 1973 and the provisions of R. 29(2) EPC 1973 (R. 43(2) EPC) had to be construed in opposition proceedings in the light of the finding in G 1/91, point 4.2 of the Reasons. R. 29(2) EPC 1973 (R. 43(2) EPC) should not constitute an obstacle to defending the patent in all its branches (cf. T 263/05 and T 1416/04). The board emphasised that it was not questioning the general applicability of Art. 84 EPC 1973 as to conciseness or of R. 29(2) EPC 1973 (R. 43(2) EPC) in opposition proceedings. It merely considered that these norms did not apply to sets of claims whose subject-matter was already claimed in the granted version of the patent.

According to the board in T 1416/04, a request containing a plurality of independent product claims might be allowable under R. 57a EPC 1973 (R. 80 EPC) in order to provide an amendment of a granted set of claims containing only one independent product claim, if the amended independent claims arose from the deletion of previous claims. With regard to the form of the claims, the board did not consider it relevant for the case before it to decide whether R. 43(2) EPC applied to opposition cases or not: even if R. 43(2) EPC should be considered applicable, the subject-matter in the granted claims could not appropriately be covered by one independent claim so that the requirements of this rule would have been met anyway.