Once a decision to grant has been issued, the European examination procedure is closed and the outcome is binding on the applicant and the EPO in so far as no further amendments - save for corrections under R. 140 EPC (former R. 89 EPC 1973) - may be made. However, if an opposition is filed, the patent in suit may be amended. Although patent proprietors are not free to make such amendments at their discretion, because opposition proceedings are not a continuation of the examination proceedings, they are entitled under R. 80 EPC (R. 57a EPC 1973) - without prejudice to R. 138 EPC (R. 87 EPC 1973) - to respond to an opponent's objections by amending the description, claims and drawings, provided that the amendments are occasioned by grounds for opposition specified in Art. 100 EPC (substance unchanged), even if the respective ground has not been invoked by the opponent. The new provisions also apply to all proceedings pending on that date. R. 80 EPC is thus applied as lex specialis to amendments in opposition proceedings.
Any amendments made in opposition proceedings must be occasioned by the grounds for opposition specified in Art. 100 EPC. It is not necessary, however, for the ground for opposition in question actually to be invoked by the opponent. For example, in opposition proceedings admissibly brought on the grounds of non-patentability, the patent proprietor can also submit amendments to remove added subject-matter (Guidelines D-IV, 5.3). In opposition proceedings, the patent proprietor may likewise file one or more alternative sets of claims on which the opposition division may base a decision to maintain the patent in amended form, listing those claims in order of preference (Guidelines H-III.3, June 2012 version).
In T 323/05 the board stated that R. 80 EPC (former R. 57a EPC 1973) established a limit to the amendments which could be made to the patent in suit, namely the amendments had to be occasioned by grounds of opposition specified in Art. 100 EPC, even if the respective ground had not been invoked by the opponent. Art. 84 EPC 1973 and R. 80 EPC were the two provisions which had to guide the patent proprietor when he was invited by the opposition division to adapt the description. In other words, the amendments had to be appropriate and necessary, and nothing more.
At the opposition stage, the grant of a patent does not constitute a general cut-off point in that the patent has to be defended in unamended form, but amendments are admissible only as a reaction to actual or possible grounds of opposition or to conflicting earlier national rights. Compliance with the restrictions imposed by R. 80 and 138 EPC was thus a prerequisite for any further considerations as to possible substantive cut-off effects for amendments after grant during opposition proceedings. Such substantive cut-off effects, in the board's view, could only be based on Art. 123(3) EPC (T 1149/97, OJ 2000, 259; see also Chapter II.E., Amendments).
In T 993/07 the board interpreted R. 80 EPC to mean that in opposition proceedings the proprietor's right to amend the patent, e.g. the claims as granted, is limited to making amendments in order to overcome an objection based on a ground for opposition as specified in Art. 100 EPC, thereby possibly avoiding revocation of the patent. In line with this interpretation, the board stated that opposition proceedings were not to be understood as an opportunity for the proprietor to fix any, from his perspective, shortcomings in the patent, such as an insufficient number of independent and/or dependent claims in order to define all commercially valuable embodiments. The fact that the addition of one or more independent and/or dependent claims may improve the fall-back positions in any future revocation proceedings before a national court was clearly not the scope and purpose of either R. 80 EPC or the opposition procedure.
The opposition division's decision to admit into the proceedings an auxiliary request (main request in the appeal proceedings) filed during the oral proceedings was challenged before the board in T 491/09. In its decision the board concluded that the opposition division had exercised its discretion according to R. 116(1) and (2) EPC by taking into account the following criteria:
a) prima facie allowability: contrary to the opponent's/appellant's argument that the opposition division should have examined the prima facie clarity of the claims, it was evident from the minutes of the oral proceedings that no such objections had been raised. Also, the board could not share the appellant's view that the opposition division should ex officio have examined the entire claim for clarity, following the principles of T 1459/05 and T 656/07. Apart from the fact that T 656/07 was issued after the oral proceedings at the opposition stage and that, in general, the opposition division could hardly be expected to receive knowledge of any single decision immediately after its deliverance, the board could not find any fault with the opposition division not following a decision which expressly stated that it concerned a very particular case and thus warranted a departure from otherwise consistent case law.
b) procedural expediency/abuse of procedure: the board recognised that the respondent/patent owner needed quite some prompting to finally come up with its late-filed request which addressed the point under discussion during the oral proceedings before the opposition division, but could not see an abuse of procedure therein, nor an unwarranted advantage for the respondent.
c) reasonable expectation that the opponents familiarise themselves with the proposed amendments in the time available: the minutes revealed that the oral proceedings had been conducted properly and towards the resolving of the outstanding issues, giving the opponent ample opportunity to familiarise itself with the amended subject-matter.
Since the EPC does not provide for surrender of the patent in opposition proceedings, so that - even if they issue an express statement to that effect - patent proprietors cannot surrender their patent either wholly or in part during such proceedings, they can merely request that the patent be amended. In requesting that the patent be maintained in a limited form, a patent proprietor is merely attempting to delimit it to meet objections raised by the EPO or the opponents and does not, by virtue of such limitation, irrevocably surrender subject-matter not covered by the request as limited. In principle, the patentee proprietor is free to withdraw such a request at any time during opposition proceedings or to amend it subsequently and, in particular, to resume a defence of the patent as granted, unless this would constitute an abuse of procedural law or the proprietor is prevented from doing so by the prohibition of reformatio in peius. This is established case law (see T 123/85, OJ 1989, 336; T 296/87, OJ 1990, 195; T 155/88, T 225/88, T 217/90, T 715/92, T 752/93, T 1037/96, T 445/97, T 473/99, T 880/01, T 794/02, T 934/02, T 1213/05, T 1394/05).
According to the case law in T 123/85 (OJ 1989, 336), there is nothing to stop patent proprietors who have defended only a limited version of their patent in opposition proceedings from seeking to reinstate the patent as granted in any subsequent appeal proceedings. However, this is subject to the conditions laid down in G 9/92 and G 4/93 (OJ 1994, 875; accordingly, the position taken in T 369/91, OJ 1993, 561, is obsolete).