In T 325/95 the board pointed out that the assumption that the extent of protection referred to in Art. 123(3) EPC 1973 would depend not only on the actual wording of the claims, but also on their validity in view of the prior art, was not supported by the explicit statement in Art. 69 EPC 1973 that "the extent of the protection conferred by a European patent ... shall be determined by the terms of the claims". The appellant's submissions also implied that claims amended in opposition proceedings should always have a counterpart in the set of claims as granted. The board noted that this was not in line with the consistent case law of the EPO either. Attention was drawn for instance to decision G 2/88 (OJ 1990, 93), which ruled that replacement of a granted claim to a compound or composition by a claim directed to a new use of the compound or composition was admissible under Art. 123(3) EPC 1973.

In T 81/03 the board stressed that Art. 69 EPC 1973 and its Protocol were to be applied in proceedings before the EPO whenever it was necessary to determine the protection conferred (see e.g. G 2/88, OJ 1990, 93). Equivalence considerations obviously often played a prominent role in national infringement proceedings, and although equivalents were not mentioned in the EPC 1973, they would be in the Protocol on Art. 69 of the revised Convention, EPC 2000. Nevertheless, if the opponents had been right in their allegations, it would never be possible to amend a claim during opposition proceedings since the addition of any new feature to some extent necessarily reduced the weight of the features in the claim as granted. This was particularly true when the subject-matter of the granted claim was not new. For that reason the argument could not be accepted. The board thus found that the general, abstract concern that the addition of a feature to a claim after grant led to an extended scope of protection because the resulting combination of features might give rise to a different evaluation of equivalents in infringement proceedings was not in itself a sufficient reason for not allowing the addition of limiting features under Art. 123(3) EPC 1973.

In T 177/08, with reference to Art. 123(3) EPC, the board referred to Art. 69(1), second sentence, EPC, which provides that the description and the drawings are to be used to interpret the claims. The board said that it had therefore to be decided whether said interpretation of the claims by the content of the description was limited to cases where the claims were in need of interpretation, e.g. because of functional or unclear features, or whether it also applied to the case at issue, where a well-known and generally accepted meaning of a term was overthrown and replaced by a new definition given in the description. The board was of the opinion that the second sentence of Art. 69 EPC did not apply to cases where an unambiguous and generally accepted definition of a term figuring in the claims was to be superseded by a different definition found in the description. If it was intended that a term which was in no need of any interpretation be given a new meaning, then the definition for this new meaning had to be put into the claims. Third parties could not be expected to check every single term of the claims for a potentially different meaning that might be hidden somewhere in the description. As a consequence, the board concluded that the subject-matter of the main request extended the protection conferred.

In T 547/08 the board stated that the appellant's (opponent's) arguments relating to the rights of the patent proprietor to sue for indirect or contributory infringement were not relevant to the issue of extension of the scope of protection under Art. 123(3) EPC. In G 2/88 (OJ 1990, 93) it was clearly ruled that it was not necessary to consider the national laws of the contracting states in relation to infringement and that this issue was not relevant when deciding upon admissibility of an amendment under Art. 123(3) EPC. With respect to the question of an extension of the scope of protection under Art. 123(3) EPC, it was, rather, appropriate to take into account the fact that the protection conferred by a patent was determined by the terms of the claims, and in particular by the categories of the claims and their technical features, in accordance with Art. 69(1) EPC and its protocol (G 2/88, OJ 1990, 93).

In T 1172/08 the board considered that the interpretation of the protection conferred by a patent according to Art. 69 EPC was in general not one of the duties of the boards of appeal (cf. T 175/84). For the purpose of establishing whether the amendments of the main request fell foul of the provisions of Art. 123(3) EPC, it was however necessary to do so. The board stated that claim 1 as granted and claim 1 of the main request, when read on their own, provided protection for different subject-matter. The patent proprietor agreed that normally such a shift in the extent of protection would not be allowable. It argued, however, that the case at issue was very particular because the claims as granted did not embrace the subject-matter of the only example of the patent specification. The board had no doubts and the parties did not dispute that dendritic cells and monocytes were different cell types characterised by different features. Thus, the skilled person would a priori not have had any reason to read a different technical meaning into the term "obtaining from a blood sample a solution of dendritic cells". Reading the patent proprietor's interpretation into claim 1 would require the skilled reader to completely ignore the wording of granted claim 1, which per se was not technically meaningless, with the consequence that the wording of claim 1 would merely serve as an empty shell. This was clearly not in the sense of Art. 69 EPC nor in the sense of the protocol on its interpretation. Moreover, the interest of third parties in legal certainty would be completely ignored, if the patent proprietor's interpretation were found to be acceptable. The board came to the conclusion that the main request did not meet the requirements of Art. 123(3) EPC.

In T 2284/09 the effect of the amendment of claim 1 was to enlarge the scope of protection conferred by the claim as compared to the patent as granted. This contravened Art. 123(3) EPC. The appellant (patent proprietor) had relied upon decision T 108/91 (OJ 1994, 228), according to which, in the case of inconsistency between the claim and the totality of the disclosure, it was permissible to refer to the description and, pursuant to Art. 69(1) EPC, to rely on the disclosure of the description to amend the claim. T 108/91 was however not applicable in the case at issue, since there was no inconsistency between the claim of the granted patent and the description. Furthermore decision G 1/93 (OJ 1994, 541) ruled that in the case of a non-disclosed limitation being introduced during examination proceedings (as was the case here), it was not permissible to remove it when so doing would extend the scope of protection. In G 1/93 the role of Art. 69(1) EPC was also considered and it was concluded that the description was to be used for assessing in particular sufficiency of disclosure and in determining the scope of protection conferred by the claims. However, there was no finding in G 1/93 that supported the position of the appellant that the description might be used as a repository from which amendments to the claims could be derived even if such amendments would contravene Art. 123(3) EPC.

In T 1736/09 the board held that, in determining whether amendments made in opposition proceedings complied with the requirements of Art. 123(3) EPC, the protection conferred by European patent was determined by the claims of the granted patent, the description and drawings of the granted patent being used to interpret the claims in accordance with Art. 69(1) EPC and its Protocol. For the purpose of examination under Art. 123(3) EPC it was irrelevant whether the granted patent met the requirements of Art. 123(2) EPC or Art. 76(1) EPC. See also T 2186/12.

In T 1896/11 the appellant submitted that, taking Art. 69 EPC into account, the description had to be used to interpret the claims; since the protection conferred by claim 5 of the patent as granted necessarily extended to what was stated in the description, claim 5 could be corrected to reflect the description without infringing Art. 123(3) EPC. However, the board held that, in the case at issue, the description could not be used to give a different meaning to a claimed method step which in itself imparted a clear, credible, technical teaching to the skilled reader. Otherwise third parties could not rely on what the claim actually stated. In order to determine whether the claimed method step in itself imparted a clear, credible technical teaching, it was necessary to examine "whether (a) the step as claimed was in itself meaningful and plausible from a technical point of view, and (b) whether there was, prima facie, any inherent incompatibility with the remaining features of the claim" (see T 1202/07). In the case in hand, the relevant feature was meaningful and plausible from a technical point of view.