Numerous decisions, in particular T 1002/92 (OJ 1995, 605), have looked at the extent to which the principles set out by the Enlarged Board of Appeal in G 9/91 and G 10/91 (OJ 1993, 408 and 420) with regard to the admissibility of fresh grounds of opposition influence the admissibility of late-filed new "facts, evidence and arguments" in support of grounds of opposition already contained in the notice of opposition.
In the landmark decision T 1002/92, the board reached the following conclusion: in proceedings before the opposition divisions, late-filed facts, evidence and related arguments which go beyond the "indication of the facts, evidence and arguments" presented in the notice of opposition pursuant to R. 55(c) EPC 1973 in support of the grounds of opposition on which the opposition is based should only exceptionally be admitted into the proceedings if, prima facie, there are clear reasons to suspect that such late-filed material would prejudice the maintenance of the European patent in suit.
The criteria governing the admission of late-filed facts, evidence and arguments are more restrictive and stringent in proceedings before the boards of appeal than in opposition proceedings at first instance.
In T 1002/92 the board held that in contrast to the first-instance proceedings, the appeal procedure is a judicial procedure and therefore "less investigative". Therefore, as regards proceedings before the boards of appeal, new facts, evidence and related arguments which go beyond the "indication of the facts, evidence and arguments" presented in the notice of opposition pursuant to R. 55(c) EPC 1973 in support of the grounds of opposition on which the opposition is based should only very exceptionally be admitted into the proceedings in the appropriate exercise of the board's discretion and if such new material was prima facie highly relevant in the sense that it could reasonably be expected to change the eventual result and was thus highly likely to prejudice maintenance of the European patent in suit. In addition other factors relevant to the case, in particular whether the patentee objected to the admissibility of the new material and the reasons for any such objection, and the degree of procedural complication that its admission was likely to cause, should be taken into account. In general the later such new material was filed, the greater the degree of procedural complication it was likely to cause.
In T 609/99 the board stated that despite the proprietor's objection to the admission of evidence which had been disregarded in the opposition procedure pursuant to Art. 114(2) EPC 1973, the board might, in certain circumstances, take account of this evidence without any implication that it was prima facie highly relevant. This exercise of discretion was not inconsistent with the criteria set out in T 1002/92. In the circumstances of the case at issue the board's admission of evidence had not extended the legal and factual framework.
In T 874/03 the board, considering a prior-art document, which was first filed at the oral proceedings before the board, acknowledged that it was immediately apparent that this fresh material might represent the closest prior art. In accordance with Art. 10b(3) RPBA 2003 (Art. 13(3) RPBA), such facts and evidence might not in principle be admitted into the proceedings because their admission would lead to an adjournment of the proceedings. However, an exception to the above principle was justified if the patent proprietor agreed to the admission of the fresh material. The board stipulated that, as emphasised by the Enlarged Board in G 9/91 (OJ 1993, 409), it might in some cases be in the patent proprietor's own interest that such facts and evidence were not excluded from consideration in the centralised procedure before the EPO. It pointed out that such fresh material had to be prima facie highly relevant in order to be admitted into the proceedings exceptionally with the agreement of the patent proprietor (T 369/08).
In T 931/06 the board stated that when assessing inventive step, a late filed document may be considered if it belongs to the same or a closely related technical field and discloses subject-matter conceived for the same or a similar purpose as the contested patent. In the light of T 1002/92 such a document would then be prima facie relevant in the sense that it might prejudice the maintenance of the patent, at least in unamended form.