In T 736/95 (OJ 2001, 191) the ground referred to by the appellant under Art. 100(c) EPC had not been raised in the notice of opposition. The opposition division had decided not to admit the newly submitted ground, without giving the parties any indication that it considered it to be less pertinent. The question which then arose was whether the fresh ground could be examined at all under Art. 114(1) EPC. Having regard to the Enlarged Board of Appeal's decisions in G 10/91 (OJ 1993, 420) and G 1/95 (OJ 1996, 615) and to the Guidelines for Examination in the EPO, the board concluded that the department of first instance at least had to examine whether a fresh ground was relevant and could therefore prejudice maintenance of the patent. Since it did not do so, but based its refusal to admit the ground only on the fact that it had been raised late, the opposition division deprived the appellant of the opportunity to have the relevance of this ground, and thus its admissibility, examined on appeal.
According to the board in T 520/01, where a ground was substantiated within the opposition period and the party which had raised the ground neither appeared at the opposition oral proceedings nor withdrew the ground, the ground had to be dealt with by the opposition division and could be taken up by other appellants in subsequent appeal proceedings.
In T 433/93 the board held that, in all normal cases, if an opposition division decided to introduce a new ground for opposition into the proceedings in addition to the ground(s) for opposition which the opponent had raised and substantiated in the notice of opposition, this should be done in writing as early as possible in the proceedings. The written notification to the patent proprietor from the opposition division informing the proprietor that a new ground for opposition would be introduced into the proceedings should at the same time ensure that the proprietor was informed not only of the new ground for opposition (i.e. the new legal basis for the opposition), but also of the legal and factual reasons (i.e. its substantiation) that would in effect substantiate the new ground which would lead to a finding of invalidity and revocation, so that the proprietor was fully informed of the case which he had to meet, and had a proper opportunity to present comments in reply. If, in a very exceptional case, an opposition division decided for the first time during oral proceedings that a new ground of opposition should be introduced into the proceedings, it would in principle be appropriate, even during oral proceedings, for the opposition division to notify the proprietor in writing both of the introduction of the new ground and of the legal and factual reasons which substantiated such a new ground. In this way, possible misunderstandings would be avoided, and the notification would be part of the written file record of the case.
In T 620/08 the opposition was originally based on the ground of lack of inventive step alone but, later in the opposition proceedings, the opponent submitted documents and arguments that the subject-matter of the patent in suit lacked novelty. In its decision, the opposition division set out in detail under the point "Novelty" the reasons why it considered that the subject-matter of the patent in suit was novel over these documents, which then led to its decision not to admit the late-filed ground for opposition. The patentee argued before the board of appeal that, since it had not been admitted into the proceedings by the opposition division, the objection of lack of novelty was a fresh ground for opposition which could not be introduced without the agreement of the patentee. Approval was not given. In the board's view, the term "fresh ground of opposition" in G 10/91 means a ground which is relied upon for the first time in appeal proceedings. This, however, was not the case here. Novelty as a ground for opposition was relied upon and discussed during the opposition proceedings, thus forming a major part of the decision under appeal. Furthermore, a board of appeal is at least not barred from considering a late-filed ground for opposition which has been disregarded by the opposition division pursuant to Art. 114(2) EPC, if it is of the opinion that the opposition division exercised its discretion wrongly in this respect. The procedural decision of an opposition division to disregard submissions forms an essential element of its decision-making process and belongs as such to the issues subject to review when the final decision of the opposition division is challenged on its merits.