a) General 

Pursuant to R. 80 EPC (R. 57a EPC 1973) the claims of a granted patent may be amended, provided that the amendments are occasioned by a ground for opposition under Art. 100 EPC, even if that ground has not been invoked by the opponent. Prior to the introduction of R. 57a EPC 1973 (entry into force on 1 June 1995, see decision of the Administrative Council, OJ 1995, 9), it had already been clarified in the case law that the EPC did not guarantee a patent proprietor the right to have proposed amendments admitted in opposition (appeal) proceedings. Whether to allow such amendments was to be decided by the department concerned exercising due discretion. Amendments could be refused if they were neither appropriate nor necessary (see e.g. T 406/86, OJ 1989, 302). For later decisions referring to these criteria within the framework of R. 57a EPC 1973 (R. 80 EPC), see e.g. T 17/97, T 313/98, T 994/03, T 263/05, OJ 2008, 329, T 323/05, T 340/10, T 2063/15.

As underlined in T 256/19 with reference to the notes on the introduction of R. 57a EPC 1973 (Notice dated 1 June 1995, OJ 1995, 409), R. 80 EPC addresses the purely substantive aspects of the proprietor's entitlement to amend the patent, and does not specify the point in time up to which amendment is allowed (on "Late submission of amendments" and in particular discretion regarding their admittance, see chapter IV.C.5.1.4 below). In the board's view, the wording of R. 80 EPC (in particular "may be amended, provided that") meant that claims may be amended if the amendments are occasioned by an opposition ground; they may not be amended otherwise. The requirement of R. 80 EPC was therefore similar to that of Art. 123(2) EPC (see in particular "may not be amended in such a way that"). Accordingly, the board considered R. 80 EPC to be a non-discretionary provision with a substantive requirement that relates to the allowability of a patent as amended rather than to admissibility.

According to T 323/05, which concerned a request to adapt the description, R. 57a EPC 1973 (R. 80 EPC) established a limit to the amendments which can be made to the patent in suit. Art. 84 EPC 1973 and R. 57a EPC 1973 were the two provisions which have to guide the patent proprietor when invited by the opposition division to adapt the description. In other words, the amendments have to be appropriate and necessary, and nothing more.

In T 750/11 the board observed that amendments under R. 80 EPC were formally admissible so long as they could be regarded as a serious attempt to overcome a ground for opposition. So an amendment further limiting the subject-matter of an independent claim complied with R. 80 EPC in formal terms. Whether it actually overcame any ground for opposition was a separate matter to be settled as part of the ensuing substantive examination. A serious attempt was acknowledged in e.g. T 1175/11 and T 1797/16. For a counter-example, see T 1833/15 (in which the amendment did not change the claimed subject-matter and so did not amount to a serious attempt).

In T 993/07 the board recalled that R. 80 EPC is lex specialis for amendments during opposition proceedings, analogous to R. 137 EPC for amendments during examination proceedings. The board interpreted the rule 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 (confirmed in T 21/16 and referred to as established case law). 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 (confirmed in T 1764/17). The board also observed that a limitation procedure pursuant to Art. 105a EPC is not subject to the same requirement as set out in R. 80 EPC.

In T 359/13 the board stated that R. 80 EPC did not place any restriction on the form of amendments a patent proprietor may (seek to) make to address objections raised (here: reformulating the product claim as a use claim). On the contrary, a patent applicant or proprietor was free to draft proposed amendments to the specification in any manner considered appropriate. Even in the situation considered in G 1/99 where the requirements of the principle of no reformatio in peius imposed restrictions on the manner in which the claims may be amended, an opponent as appellant had no right to prescribe the form of the amendments which the patent proprietor as respondent may make (see T 23/04).

In T 1285/15 the board underlined that the very language of R. 80 EPC ("... occasioned by a ground for opposition ...") made clear that the situation at the time of the amendment needed to be considered when compliance with this provision was examined. The fact that, as in the case in hand, the claims were amended again at a later stage and that, as a consequence, the deletion of the sentence was no longer required, did not lead to the conclusion that the amendment of the description retroactively contravened R. 80 EPC. The original amendment could still be said to have been occasioned by a ground for opposition.

In T 946/16 the board found that the opponents' objection was based on a misinterpretation of R. 80 EPC. The amendments referred to in this Rule were not ones made to an earlier version differing from the patent as granted. The result of interpreting R. 80 EPC that way would be incompatible with the spirit and purpose of the EPC. Among other things, it would make it impossible for the patent proprietor ever to overcome a clarity objection to an amendment which was itself in line with R. 80 EPC.

In T 2450/17, paragraph [0008] of the patent specification contained an incorrect reference to the prior art as a result of an amendment during the grant proceedings. At the oral proceedings before the board, the appellant submitted an amended paragraph [0008], from which the inaccurate information had been deleted. As to whether the contested amendments were admissible under R. 80 EPC, the board pointed out that the case law had recognised that references to relevant prior art as defined in R. 42(1)(b) EPC could be added at a later stage without this necessarily being deemed an inadmissible extension of the subject matter of the application. However, such references designed to delimit the relevant prior art should not be incorrect or misleading, otherwise they could indeed alter the subject-matter of the patent. Remedying inaccuracies of this kind thus did not contravene Art. 123(2) EPC; on the contrary, doing so was appropriate and necessary for ensuring compliance with that provision. Deleting incorrect information about the prior art from which the patent specification was to be distinguished was thus appropriate for addressing the ground for opposition under Art. 100(c) EPC. The board also concluded that it was wrong to say that any amendment to an incorrect reference to the prior art permitted under R. 80 EPC (as it was occasioned by Art. 100(c) EPC) automatically constituted a breach of Art. 123(3) EPC. It noted that R. 80 EPC was satisfied if the patent documents were amended to overcome a potentially relevant ground for opposition and that, in the case in hand, the scope of protection had not been extended.