In G 1/24 decision, the Enlarged Board of Appeal (EBoA) of the European Patent Office (EPO) confirmed that, when assessing patentability, the claims are the starting point and basis for assessment. However, the description and drawings must always be consulted when interpreting those claims.
G 1/24 therefore moved away from a strict “claims alone” approach to claim interpretation. However, while the decision confirmed that the description does play a role in determining the meaning and scope of the claims, an important question remains: how far can the description influence that interpretation?
That question now lies at the heart of G 1/26 referral, together with an important related issue concerning how claim interpretation should be approached when assessing added matter under Article 123(2) EPC.
Background to the G 1/26 referral
The referral arose from T 873/24, concerning a patent directed to a pre-coated steel strip. One feature of the claim required the ratio of titanium to nitrogen in the steel to be greater than 3.42, but did not specify what type of ratio was intended.
Read in isolation, the claimed ratio could be understood in different ways, including as a molar ratio or a weight ratio. When the specification was considered as a whole, however, the skilled person could be led towards one particular interpretation, namely a weight ratio.
Against this background, a series of questions have been referred to the EBoA.
The first question is procedural and concerns when a decision on a point of law may be considered “required” for the purposes of a referral to the EboA under Article 112(1)(a) EPC. Clarification on this procedural issue would be welcome, although the questions of greater practical significance for applicants and patentees concern claim interpretation (Question 2) and added matter (Question 3).
Question 2: How far can the description influence claim interpretation?
Questions 2(a) and 2(b) ask:
“2.(a) Does the fact that the claims are the starting point and the basis for assessing the patentability of an invention generally preclude a feature which is only disclosed in the description or the drawings of a patent from being read into the meaning of a granted claim, in particular if this leads to a restrictive reading of terms used in the claim?
2.(b) If the answer to question 2.(a) is no: is claim interpretation the result of both reading the claims and consulting the description and drawings as a unitary process and does the claim being the starting point and the basis for assessing the patentability rule out only those interpretations which can be derived from the patent as a whole but would clearly contradict the general technical understanding of the terms used in the claim?”
In short, Question 2(a) asks whether a feature found only in the description or drawings can be used to narrow the meaning of a granted claim.
Interestingly, this point was discussed in the related decision G 1/25, in which the EBoA considered the role of the description and drawings in claim interpretation:
“The description and drawings may affect the meaning which the skilled person attributes to the claim wording, but they cannot be used to impose on the claim a limitation or expansion for which the claim wording provides no basis. In line with this approach, a person skilled in the art reading the claim in the context of the description and drawings will try to take a definition found in the description at face value. As long as the definition is technically reasonable and complies with the overall teaching of the claims, description and drawings, the skilled person will read terms in the claim in the sense of the definition, taking into account both the broadening and limiting aspects.”
(G 1/25, Reasons 10)
This appears to be in tension with the current EPO Guidelines for Examination, which state:
“However, when assessing patentability, the description and drawings cannot be relied on to read into the claim a restrictive feature not suggested by the wording of the claim.
If, on the other hand, the description provides a special broad definition of a term used in a claim, the claim must be interpreted in the light of that broad definition when assessing patentability, provided this interpretation is technically meaningful.”
The current Guidelines therefore appear to draw a distinction between broadening and limiting definitions, whereas the wording of G 1/25 expressly contemplates taking account of both. Importantly, the current Guidelines were published before the decision in G 1/25 was issued. As the Guidelines are not themselves binding legal authority, it may therefore be that G 1/25 has already provided at least part of the answer to Question 2(a). Nevertheless, express clarification from the EBoA in G 1/26 would be welcome, particularly as to the extent to which a definition or feature found in the description may restrict the meaning of the claim.
Question 3: What does this mean for added matter?
Questions 3(a) and 3(b) apply the issue of claim interpretation specifically to added matter under Article 123(2) EPC:
“3.(a) When assessing compliance with Article 123(2) EPC, must a term used in a claim be assessed against all interpretations that make technical sense to the skilled reader on the basis of the claim alone?
3.(b) If the answer to question 3.(a) is no: is it sufficient that only the interpretations of the subject-matter of the claim established against the background of the patent specification as a whole are directly and unambiguously derivable from the application as filed?”
The issue can therefore be stated quite simply: must every technically sensible interpretation of the claim, read alone, have basis in the application as filed, or only the interpretation reached when the specification is considered as a whole?
Returning to T 873/24, the distinction is important because the competing interpretations of the ratio of titanium to nitrogen lead to different conclusions when assessing added matter under Article 123(2) EPC. The weight ratio interpretation had basis in the application as filed, whereas the alternative molar ratio interpretation would raise an added-matter objection.
If Question 3(a) is answered yes, both interpretations could therefore need to satisfy Article 123(2) EPC, even if consideration of the specification as a whole pointed the skilled person towards only one of them.
If the answer is no, only the interpretation established against the background of the patent specification as a whole would need basis in the application as filed. In T 873/24, this would mean that, if the specification establishes the claimed ratio as a weight ratio, only that interpretation would need to satisfy Article 123(2) EPC.
That distinction could have important consequences for amendments before the EPO. An amended claim might otherwise fall foul of Article 123(2) EPC merely because, when read in isolation, it admits another technically sensible interpretation for which there is no basis, even though the specification as a whole points the skilled person towards a supported interpretation.
What could G 1/26 mean in practice?
G 1/24 established that the description and drawings must always be consulted when interpreting claims. G 1/26 could now clarify how far they can influence that interpretation, including the consequences for added matter.
It remains to be seen whether the EBoA will take up the referral. If it does, the answers should provide welcome clarification on the balance between the primacy of the claims and the role of the description in European patent practice.
Bradley Wilson
This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.
© Withers & Rogers LLP November 2026
