2.2.1 Introduction

According to Art. 99(1) EPC notice of opposition must be filed within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin. Notice of opposition is not deemed to have been filed until the opposition fee has been paid. In the interests of legal certainty, the Convention lays down certain further requirements that must be met before the opposition period expires, in particular that the notice of opposition is filed in a written reasoned statement (R. 76(1) EPC) and that it sufficiently identifies the opponent (R. 76(2)(a) EPC) and the patent opposed (R. 76(2)(b) EPC), that it states the extent to which the patent is opposed and the specific grounds, and that it indicates the facts and evidence presented in support of these grounds (R. 76(2)(c) EPC). Fulfilment of the requirements of R. 76(2)(c) EPC (R. 55(c) EPC 1973) is not only essential for the admissibility of the opposition. They also establish the legal and factual framework of the opposition (see G 9/91 and G 10/91, OJ 1993, 408 and 420).