8.3.3.2 Procedure in opposition proceedings 

If new facts or evidence are submitted during inter partes oral proceedings which a party, although duly summoned, fails to attend, it must first be examined whether these submissions may be disregarded (Art. 114(2); see also E‑VI, 2).

Following G 4/92, if new facts are taken into consideration, then at the end of the oral proceedings a decision based on these facts cannot be taken against the absent party. Further, new evidence can only be used against the absent party if it has been previously notified and merely supports the previous assertions of the party who submits it. However, new arguments may be used at any time, in so far as they do not change the grounds on which the decision is based.

In other words, what the Enlarged Board of Appeal ruled out in G 4/92 was the possibility of taking decisions against the absent party on the basis of a surprising course of events at the oral proceedings, which changes the legal and factual framework of the case in an unforeseeable way (see T 414/94).

An absent party cannot be considered taken by surprise if during oral proceedings the other side attempts to overcome objections raised before the oral proceedings. In particular, a submission during oral proceedings of a more restricted and/or formally amended set of claims with a view to overcoming the objections of the opponent is not considered a "new fact" (see T 133/92 and T 202/92). Nor is it unexpected that amended claims are examined for formal admissibility and for compliance with Art. 123(2) and Art. 123(3) (see T 341/92).

In the particular case of an absent opponent, if new prior art is submitted for the first time during oral proceedings which may be an obstacle to the maintenance of the opposed patent, this new prior art can be taken into consideration despite the opponent's absence because it is in the opponent's favour (see T 1049/93).