The European Patent Office (EPO) has resolved an internal split of opinions regarding when issues of lack of clarity can be raised in opposition appeals. On March 24, 2015, the Enlarged Board of Appeal (EBA) held that lack of clarity under Article 84 of the European Patent Convention (EPC) may be considered during EPO oppositions and appeals only to the extent that an amendment introduces non-compliance with that article. The decision was rendered in Case G3/14, which was a referral from a Technical Board of Appeal. The 93 page decision is here.

Lack of clarity is not a ground for filing an opposition in the EPO. The Opposition Divisions and Appeal Boards ordinarily lack authority to consider lack of clarity issues, except when deciding whether to permit amendment of a claim during their proceedings. The decision in G4/13 rejects the view of some Technical Boards that, once a claim has been amended and a lack of clarity issue was raised, all aspects of clarity in the amended claims should be considered. Persons supporting that approach had suggested that it is a permissible interpretation of the EPC and that the EPO should not permit patents to emerge from oppositions and appeals with known questions of clarity.

The G4/13 decision also is notable as a relatively rare example of the EBA resolving a major issue. (Another example is the EBA decision on the following day in G2/13 (“Broccoli II”)). The EPC gave the individual Boards of Appeal a high degree of independence. The EBA has limited authority to decide cases referred to it by an individual Board, of by the EPO President or by petition from a party, to ensure uniform application of the law or to address a point of law of fundamental importance. There is no direct judicial review of decisions of EPO Boards comparable to an appeal to the Federal Circuit in the United States. Persons wanting to challenge European Patent claims on lack of clarity grounds can only do so today in invalidity proceedings in a national court. The EU Unified Patent Court (UPC), which appears likely to open in 2016, will be an alternative forum for invalidity proceedings, including those based on lack of clarity.