R. 80 EPC (former R. 57a EPC 1973) addresses purely substantive aspects of the proprietor's entitlement to amend his patent, and does not specify the point in time up to which amendment is allowed; here existing practice remains unchanged. This restriction of the right to amend is in line with the object and purpose of opposition proceedings, and does away with the need for a discretionary provision like R. 137(3) EPC (former R. 86(3) EPC 1973) (see Notice from the EPO dated 1.06.1995 concerning amendment of the EPC 1973, the Implementing Regulations and the Rules relating to Fees, OJ 1995, 409).
As already mentioned, the boards of appeal have derived, in particular from R. 79(1) EPC (former R. 57(1) EPC 1973), the principle that the proprietor has no right to have amendments admitted in any stage of opposition proceedings. At the discretion of the opposition division or the board of appeal, amendments can be refused if they are neither appropriate nor necessary. In particular, late-filed amendments can be refused if they are not a fair attempt to overcome an objection made. In general, the question whether an amendment is appropriate can only be answered on the basis of its content, i.e. after it has actually been submitted. To refuse any further amendment is only appropriate if it is evident after various unsuccessful amendments that the proprietor is not seriously trying to overcome the objections but is only delaying the proceedings (T 132/92).
Claims filed late (i.e. just before or at the hearing) are subject to the same principles in opposition proceedings as in appeal proceedings. In T 648/96 the amendments requested in oral proceedings before the opposition division were simply a response to arguments put forward. The board said EPO deciding instances have a discretion to consider documents (including claims) filed in particular during oral proceedings, if they respond to the instance's or the opponent's objections, or are clearly grantable. Undesirable delays in the proceedings should, however, be avoided.
In T 382/97 the appellant (patentee) came up with three auxiliary requests only at the beginning of oral proceedings. The appellant tried to justify disregarding the time limit set by the opposition division under R. 116 EPC (former R. 71a EPC 1973) by citing R. 80 EPC (former R. 57a EPC 1973) which, it asserted, "was created as a lex specialis for amendments during opposition proceedings" and did not "specify the point in time up to which the amendment is allowed". Indeed, the board agreed that R. 57a EPC 1973 explicitly established the patent owner's right to amend its patent according to the criteria laid down in that rule. However, the board could not accept the appellant's argument that the absence of a time limit in R. 80 EPC entitled a patent proprietor to submit amendments to its patent at any time, i.e. also during oral proceedings, without good reason. In the board's judgment, R. 80 and 116 EPC together governed the procedural preconditions for amendments to a patent by its proprietor before the opposition division, which amendments of course had to comply with Art. 123(2) and (3) EPC: R. 80 EPC created the legal basis for amendment, and R. 116 EPC governed the deadline for doing so. The board emphasised in this connection that amendments not complying with a time limit set under R. 116 EPC might nevertheless be admissible if there were good reasons for their late submission. Finally, the board noted that the patent owner's right to amend its patent under R. 80 EPC did not equate to an automatic right to file additional auxiliary requests. Any amendment had to be carried out in the most expedient manner, which had to be established by the opposition division, taking into due account the interests of all parties.