As early as T 117/86 (OJ 1989, 401), it was pointed out that facts and evidence in support of an opposition which were presented after the nine-month period had expired were out of time and late, and might or might not be admitted into the proceedings as a matter of discretion under Art. 114(2) EPC 1973. Boards had to ensure that proceedings were conducted expeditiously, and other parties fairly treated. The parties should submit all the facts, evidence and arguments relevant to their case as early and completely as possible, particularly when such an evidence was already known to the party concerned (see T 101/87; T 237/89; T 951/91, OJ 1995, 202; T 34/01; T 1182/01; T 927/04; T 1029/05).

In T 188/05 the board did not share the appellant (opponent's) view that it was obliged to admit relevant evidence irrespective of how late it had been filed, provided that it cast doubt on the patent's validity. The case law of the boards of appeal establishes quite clearly that the first instance and the boards of appeal have a discretion to admit late-filed submissions and that the exercise of this discretion depends on the facts of each case but pertinent matters may include the relevance of the new material, whether it could have been produced before and if so why it was not, whether other parties and/or the board itself are taken by surprise, and how easily they can and whether they have adequate time to deal with it (see also T 1774/07, T 424/11).

In T 1449/05 the board stated that the discretion to permit amendment of a party's case may be exercised against a proprietor who seeks to resile at a late stage in the opposition appeal procedure from a previous long-standing acknowledgement or persistent tacit admission of prior art. Admitting this resilement would require in all fairness the adjournment of the oral proceedings to allow the appellant opponent to search for adequate evidence. This could have been done at an earlier stage of the proceedings (likewise T 1682/09).

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. 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 (T 369/08).

In T 1488/08 the patent had been opposed under Art. 100(a) and (c) EPC 1973. In their written statement setting out the grounds of appeal, however, the appellants had only invoked lack of inventive step. The board found that the new objections of added subject‑matter and lack of novelty had only been raised after the respondents had submitted their reply and were therefore late filed. Their attempt to re-introduce them could therefore only be regarded as a change of position determined by procedural tactics ("salami" tactics). On that basis alone, the board considered, in view of procedural economy, that it should exercise its discretion not to admit the late filed objections.