In principle, lack of clarity is not a ground for opposing a granted European Patent. However, in the instance where amendments to the granted subject-matter are made during an opposition procedure, clarity may become an issue. This is because it was already ruled in G 9/91 that such amendments must be fully examined regarding their compatibility with the requirements of the European Patent Convention (EPC). Unfortunately, to date it remains unsettled whether or not this principle is also applicable when the amendment merely consists of a literal incorporation of a dependent claim into an independent claim.
Quite recently (in decision T 459/09 from 13 December 2012), a Board of Appeal of the EPO came to the conclusion that any amendment of a substantial nature would justify an unrestricted examination as to whether or not the amended patent meets all the requirements of the EPC. This includes the requirement of clarity. In the Board’s view, such an amendment of a substantial nature occurs where dependent claims are literally incorporated into independent claims. However, whilst the Board referred to an unrestricted power to examine amendments irrespective of their origin as a “rule”, the decision itself summarizes in Nos. 4.1.4 and 4.1.5 of the section “Reasons” the factually diverging case law on this matter.
Nevertheless, the Board saw no reason to refer any questions regarding such to the Enlarged Board of Appeal to seek clarification. Perhaps Mr. Battistelli, the current President of the EPO, should step in and refer this point of law to the Enlarged Board of Appeal pursuant to Article 112(b) EPC in order to ensure uniform application of the law and to have the matter ultimately clarified.