The boards have stressed that opponents are required to submit all their objections during the opposition period, setting each out in full (T 117/86, OJ 1989, 401). Under R. 76(2)(c) EPC, the notice of opposition must contain a statement of the extent to which the European patent is opposed and of the grounds on which the opposition is based, as well as an indication of the facts and evidence presented in support of these grounds. R. 116(1) EPC provides that, when the summons to oral proceedings is issued, a final date for making written submissions in preparation for the oral proceedings must be fixed. New facts and evidence submitted after this date need not be considered, unless admitted on the grounds that the subject of the proceedings has changed. The rule confers scope for discretion (T 798/05, T 2102/08, T 1253/09).
An example of a change in the subject of the proceedings is where, in timely response to the points raised in the note annexed to the summons, the patent proprietor files amendments which have the result that a new document becomes relevant; in such a case the opponent should be allowed to present this document and must be given a chance to comment on the amendments (Art. 113(1) EPC; see also Guidelines E-II, 8.6 - June 2012 version). In T 117/02 the board stated that in the case of a request to introduce late-filed submissions (here: a new ground of opposition and new arguments and evidence) the right to be heard should be granted before those late-filed submissions were rejected.
Filing "on time" refers not only to facts and evidence submitted by the opponent within the nine-month opposition period but also to those that the patent proprietor may advance in his response to the grounds for opposition within the four-month time limit. New facts and evidence would be regarded as having been filed on time if the filing was occasioned by an argument or a point raised by another party or in the appealed decision so that, under the circumstances of the case, the new facts, documents and/or evidence could not have been filed earlier. The submission of facts and evidence within successive time limits could then also be "on time", if the principle of procedural economy has been duly observed, i.e. the submitting party has taken due care in the proceedings (T 156/84, OJ 1988, 372; T 201/92, T 238/92, T 389/95, T 532/95, T 502/98, T 468/99, T 574/02, T 320/08).