In some cases the boards of appeal have disregarded late-filed material on the grounds of abuse of procedure.

In T 951/91 (OJ 1995, 202) the board refused to take account of late-filed evidence even before it was actually submitted and pointed out that the discretionary power given to the departments of the EPO pursuant to Art. 114(2) EPC 1973 served to ensure that proceedings could be concluded swiftly in the interests of the parties, the general public and the EPO, and to forestall tactical abuse. Parties had to take into account the possibility that late-filed material would be disregarded and do their best to submit the facts, evidence and arguments relevant to their case as early and completely as possible. The board held that the submission of further fresh experimental data proposed to be filed by the appellant (opponent) some 20 months after the statement of grounds of appeal had been filed as an abuse of procedure.

In T 496/89 the board pointed out that the late introduction of documents and of other matter into the appeal proceedings is inimical and contrary to the public interest, quite apart from being unfair to the other party. Attempts by either party to spring a surprise on the other by deliberate late-filing, as well as inadvertent omissions to present arguments and the evidence needed to support them, ran counter to the spirit and intent of the Convention (see also T 430/89, T 270/90, T 741/91, T 135/98).

The board in T 718/98 decided that a party's introduction, at a very late stage of the proceedings, of evidence which could have been filed much earlier, as a strategic measure to improve its own case against the opposing party, amounted to an abuse of procedural rights and was therefore rejected independently of the possible relevance of the evidence (see also T 169/04).

In T 446/00, the board identified various forms of behaviour as abuses of procedure, including non-compliance with a procedural direction of the board requiring a party to take a certain step or steps. It was also an abuse of procedure for a party to adopt an unequivocal position on an issue and subsequently to depart from that position without explanation. That applied particularly, but not solely, in contested inter partes proceedings, in which another party was entitled to rely on that position as part of the case it had to meet (see also T 762/07).

In T 215/03 the appellant (opponent) sought to rely on a document (D24) filed approximately one year after commencing the appeal proceedings together with 25 other documents (in total about 450 pages of technical literature). The board stated that under the particular circumstances of the case, that the belated submission of evidence was not justified. To submerge, at such a late stage of proceedings, the other party and the board under a deluge of paper amounted to an abuse of procedure. The board thus decided not to admit this evidence into the proceedings regardless of its possible technical relevance.