6.3.4 Reading additional features and limitations into the claims

For the purposes of judging novelty and inventive step, the description cannot be relied on to read into the claim an implicit restrictive feature not suggested by the explicit wording of the claim (T 1208/97, T 945/99, T 681/01, T 881/01, T 1105/04, T 223/05, T 1736/06, T 299/09, T 58/13, T 617/18, T 1648/18, T 1266/19, T 530/20). In proceedings before the EPO, where the patentee has the opportunity of cutting down the claims to accord with stricter limits given in the description, the scope of a claim should not be cut down by implying into it features which appear only in the description, as this would deprive claims of their intended function (T 881/01).

In T 121/89 the board used the description to interpret an ambiguous term ("loose ignition charge"), but at the same time stressed that only features recited in or deducible from the claims could be set forth to distinguish the invention from the state of the art. The examples cited in the description did not limit the scope of the claims unless they were explicitly mentioned in them. See also T 544/89.

In T 932/99 claim 1 was directed to a product per se. The claim defined only the structure of a membrane as such, independently from its installation in an apparatus for gas separation. The board pointed out that, for this reason, the indication in the claim "capable of separating oxygen from oxygen-containing gaseous mixture" merely served the purpose of defining a capability of the claimed membrane, without imparting any limitations on any actual use of the structure claimed. The respondents had argued that, if claim 1 was interpreted in the light of the description, those limitations would be apparent. However, the board held that a distinction had to be drawn between, on the one hand, the fact that it might be necessary to take into account any explicit definition as given in the description for interpreting a claim's term and, on the other hand, the attempt to use Art. 69 EPC 1973 as a basis for reading limitations derived from the description into claims in order to avoid objections based on lack of novelty or inventive step. The latter approach to interpretation, whereby features mentioned only in the description were read into claim 1 as necessary limitations, was incompatible with the EPC (referring to T 1208/97). See also T 2049/07.

In T 1018/02 the board emphasised that, although a claim must not be interpreted in a way which was illogical or did not make sense, the description could not be used to give a different meaning to a claim feature which in itself imparted a clear, credible technical teaching to the skilled reader. This also applied if the feature had not been initially disclosed in the form appearing in the claim. Otherwise, third parties could not rely on what a claim actually states and Art. 123(2) EPC would become meaningless in respect of amendments to the claims. See also T 373/01, T 396/01, T 821/20, T 42/22.

In T 1404/05 the board stated that Art. 69 EPC and its Protocol were intended to assist a patent proprietor in contending for a broader interpretation of a claim, not for cutting down the scope of a claim. In proceedings before the EPO, if a proprietor wishes to argue for a narrow scope of the claim this should be on the basis of the wording of the claim, and not on the basis of something appearing only in the description, as in such EPO proceedings the proprietor has the possibility, subject to meeting the requirements of Art. 123(2) EPC, of restricting the wording of the claim.

In T 416/87 (OJ 1990, 415), on the other hand, the board was confronted with the situation where a feature was not included in the claims which the description on its proper interpretation specified to be an overriding requirement of the invention. The board held that, following Art. 69(1) EPC 1973 and its Protocol, the claims might be interpreted as requiring this as an essential feature, even though the wording of the claims when read in isolation did not specifically require such feature (confirmed in an obiter dictum in T 717/98). See also T 2525/11.

In T 1473/19 the board held that although Art. 69(1), second sentence, EPC requires that generally account be taken of the description and the drawings when interpreting a claim, the primacy of the claims according to Art. 69(1), first sentence, EPC limits the extent to which the meaning of a certain claim feature may be affected by the description and the drawings. The board pointed out that this view is fully compatible with the established case law that limiting features which are only present in the description but not in the claim cannot be read into a patent claim. The primacy of the claims also limits the extent to which the description may serve as a dictionary for the terms used in the claims.

According to the board in T 169/20, Art. 84, second sentence, EPC implicitly limits the support given by the description for interpreting the claims to the exceptional cases where such support is both necessary and possible. This support should only be resorted to in cases where the subject-matter of the invention needs to be clarified. Moreover, this support is only possible to the extent that there is a correspondence between the description and the subject-matter of the claimed invention. The support of the description should not be used to limit or modify the scope of the claimed features with respect to what a person skilled in the art would understand when reading them.

Such limitations due to the primacy of the claims were confirmed in T 73/19, T 2968/19, T 367/20, T 450/20, T 1494/21 and T 111/22.

In T 450/20 and T 1494/21 the board emphasised that under Art. 69(1) EPC the description and the drawings can only be used for interpreting features which are already present in the claims, but not for adding further – positive or negative – claim features or for replacing existing claim features by others. The board also pointed out that the application as filed usually cannot provide guidance for interpreting the claims of the patent as granted.

In T 111/22 the board held that the primacy of the claims in claim interpretation meant that in case of a clear conflict between the claims and the description, the claims took precedence. If a person skilled in the art understood a claim in a certain manner without doubt, taking into account the rules of grammar, the ordinary meaning of the terms used and common general knowledge, this understanding usually took precedence over an incidental and conflicting statement in the description, in particular if that statement was only made in the context of an alleged embodiment. The board concluded that the disputed feature could only be understood so that it was component (ii) – and not the entire amount of carbohydrate in the composition – which comprised 10-45 wt.% of palatinose. Hence, the granted claim 1 contained added subject-matter, contrary to the requirements of Art. 123(2) EPC. To overcome this objection, the appellant had replaced the disputed feature with "15-45 wt.% of component (ii), based on the available carbohydrate composition, consists of palatinose". In the appellant's view, Art. 123(3) EPC was not infringed, since the description had to be taken into account to determine the scope of protection of the granted patent by virtue of Art. 69 EPC. The board disagreed and pointed out that Art. 69(1), second sentence, EPC could not be relied upon to replace a claim feature with a different one which could only be found in the description. Reading the relevant passage of the description into the clear wording of claim 1 as granted to establish compliance with Art. 123(3) EPC would have the consequence that the wording of this claim merely served as an empty shell. This would undermine the principle stipulated in the first sentence of Art. 69(1) EPC and reiterated in decision T 1473/19 that the claims have primacy for determining the extent of protection conferred by the European patent. See also II.E.2.3.1c).