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), 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).

In T 1408/19 an erroneous citation of the publication number of document E2 had been provided in the notice of opposition filed on the last day of the nine-month period according to Art. 99(1) EPC. The board rejected the respondant's interpretation of T 344/88 that the opposition division should have been able to identify the correct publication number within the nine-month period according to Art. 99(1) EPC. It would be completely unrealistic to expect the opposition division to immediately check such errors. It followed from the normal daily operation of the EPO that the division would be assigned to the file only later, and in all likelihood would not even see the file within the opposition period. The board took the view that in the case at hand it was decisive that all material and information necessary for (possibly later on) establishing the correct publication number of E2 was submitted prior to expiry of the nine-month period according to Art. 99(1) EPC.

In T 571/22 the board endorsed the approach according to which the end of the opposition period under Art. 99(1) EPC was a fixed point in time as of which an opposition division had discretion not to admit facts and evidence submitted by an opponent (see T 1776/18, summarised below in this chapter IV.C.5.1.6). Accordingly, an opposition division had discretion not to admit facts and evidence which were not filed within the nine-month opposition period.