In T 341/92 (OJ 1995, 373) the board held that it was possible to base a decision on a ground discussed for the first time during oral proceedings which would prevent the patent being maintained as amended, at least if the stage reached in the case was such that the absent - albeit duly summoned - patent proprietors could have expected the question to be discussed and were aware from the proceedings to date of the actual basis on which it would be judged. The board did not consider itself prevented by reasons of procedural law from rendering a decision on the basis of Art. 123(3) EPC 1973, on an issue brought up by the board for the first time at the oral proceedings. It argued that the situation differed from G 4/92 in that the extension to which objection had been made arose solely from a comparison of the wordings of the respective claims according to the granted patent and the main request before the board, and therefore not from facts that had only been introduced into the case during oral proceedings.
In T 133/92 the board concluded that considering and deciding in substance on the maintenance of the patent on the basis of claims as amended during oral proceedings in the absence of the appellants (opponents) did not conflict with the opinion of the Enlarged Board of Appeal in G 4/92. The board stated that the respondent's (patentee's) restrictions to the claims removed objections already raised by the appellants. In such a situation the appellants could not have been taken by surprise, because they had reasonably to expect that the respondent would try to overcome all objections. The submission of auxiliary requests was clearly not a "fact" within the meaning of G 4/92. The board in T 771/92 held that the submission of restricted claims was neither a fact nor could it be evidence. The appellant could not be taken by surprise by the amendment made, because he had reasonably to expect that the respondent would try to overcome the objections made by the appellant during the written procedure. In cases T 912/91, T 202/92, T 856/92, T 890/92, (see also T 673/06 and T 235/08), which were based on similar facts, the board also concluded that Art. 113(1) EPC 1973 had been satisfied.
In T 1049/93 the board decided that, where a duly summoned opponent chose not to attend oral proceedings, a board of appeal could still consider prior art which might be an obstacle to the maintenance of the patent in suit. G 4/92 should not be construed as extending or prolonging the rights of a voluntarily absent party.
In case T 414/94 the board stated that there was no general prohibition on amending requests during a party's absence from oral proceedings as requested by the respondent/opponent. An absent party must expect reactions of the opposing party within the legal and factual framework of the case established prior to oral proceedings, and the possibility of decisions taking account of, and being based on, such reactions.
In T 501/92 (OJ 1996, 261) the board ruled that if a new ground for allowing the appeal based upon the facts set out in the file record was raised by an appellant for the first time as a new argument during oral proceedings from which the respondent was voluntarily absent, it would be contrary to Art. 113(1) EPC 1973 and contrary to the principles underlying G 4/92 to decide to allow the appeal on the basis of this new ground without first giving the respondent an opportunity to comment. In the case in point the appellant (opponent) submitted at the oral proceedings that the failure by the proprietor to file a formal request for maintenance of the European patent should lead automatically to revocation of the patent.
In T 892/94 (OJ 2000, 1) the board held that the right to be heard of a party absent from oral proceedings as expounded in G 4/92 could, in appropriate circumstances, be surrendered by a party declaring that it would take no further part in the proceedings. According to the board, the respondents' declaration, before the oral proceedings were held, that they would take no further part in the proceedings could only be construed as an unequivocal decision to surrender, voluntarily, their rights according to Art. 113(1) EPC 1973 and no longer to avail themselves of the opportunity to present their comments on any objections, facts, grounds or evidence which could potentially be introduced into the proceedings by the appellants or the board and which could later turn out to be decisive for the revocation of the patent.
In T 191/98 the board referred to G 4/92 and considered that the respondent, when informing it of its non-appearance, should have expected that the board would decide in substance on the patent in its granted form, taking into account any piece of evidence filed by the appellant and arguments based on that evidence, including the possibility that the line of argument based on a particular piece of evidence would be further developed during the oral proceedings.