G1/26 – A new Enlarged Board referral questions whether claims should be interpreted differently when considering patentability and added subject matter.

The Enlarged Board of Appeal’s decision on claim interpretation, G1/24, continues to provoke discussion as to how the description should be ‘consulted’ when assessing issues relating to patentability. Hot on its heels, we now have a new referral, G1/26[1], on how the description should be consulted when assessing added matter.

G1/24 issued less than a year ago and, if G1/26 is deemed admissible, it will be the second referral in less than a year that will affect how claims should be interpreted by the EPO in the future.

Background

In June 2025, the Enlarged Board issued a decision in G1/24 explaining that, when assessing patentability matters like novelty and inventive step, the claims should be interpreted in consultation with the description.  Later Technical Board decisions, have questioned how the description should be consulted when interpreting the claims. The fallout from G1/24 continues with the Enlarged Board now being asked to consider whether the description can be relied upon to interpret the claims in a manner that avoids the claim falling foul of the added matter requirements.

Added Matter and the referring decision, T 0873/24[2]

The added matter  provisions of the EPO (Article 123(2) EPC) require any amendments made to a patent or patent application to have clear and unambiguous basis in the original text. The EPO’s so-called “gold standard”[3] applied when assessing added matter is notoriously high.

The referring decision, T 0873/24, concerns a patent relating to a pre-coated steel strip.

The patent claims require the presence of a ratio of titanium to nitrogen of greater than 3.42.  However, the units of this ratio were unspecified in the claims. This contrasts with the description, which specifies that the ratio is a weight ratio.

The question of added matter, therefore, rests on whether the claim should be interpreted in the light of the description, such that it is implicitly limited to a weight ratio. The opponent argued that, since the claim is not limited to a weight ratio, it covers ratios that have no basis in the application as filed.  The patentee, on the other hand, was of the view that it is implicit that the ratio in the claim was a weight ratio, given that this was the only ratio supported by the description.

In the case at issue, the Technical Board identified three diverging strands of case law on how the description should be used to interpret the claims. The first held that the description should only be consulted to define the skilled person and their common general knowledge. The second was based on the principle that the description could not be used to broaden the claims. The third adopted a more holistic approach, requiring the claims and description to be read a whole.  This third approach was deemed to be the only approach that would support the patentee’s contention that the reference to weight ratios was an implicit feature of the claims.

The referral

Much of the decision in T 0873/24 is devoted to justifying the referral’s admissibility. This is because established case law suggests that a referral is only admissible if the Board has concluded that the patent would be maintained on all other grounds. In the referring decision, the Board has not considered the other grounds, deeming it impractical and inefficient to do so. The Board in T 0873/24, therefore, took pains to justify a lower standard for questions to be considered by the Enlarged Board.

The referred questions

The questions put by the Enlarged Board were as follows:

1.     May a decision be considered to be “required” for the purposes of Article 112(1) EPC, if the referring Board demonstrates that the point of law in question arises out of the context of the case pending before it and, in the circumstances of the proceedings, it is reasonable for the Board to examine it and decide on it next?
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?
3.    (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?
4. (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?
5. (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?

Conclusion

It remains to be seen if the Enlarged Board admits this referral and, if so, what guidance will be given for interpreting claims for the purpose of assessing added matter. Depending on the answers to the referred question, we may see yet another shift on claim interpretation. The decision may also have repercussions on the “gold standard” assessment of added matter as we currently know it.  Prior to G1/24, the bar for being able to escape added matter attacks based on implicit disclosures was typiically very high. This may change if statements in the description further reduce the primacy of the claims. If these developments come to the fore, what impact will they have on certainty for third parties?

[1] Referral to the Enlarged Board of Appeal – G 1/26 (“Coated steel strips”) | epo.org

[2] EP About this file – European Patent Register

[3] G2/10

This article was Prepared by Partner Hsu Min Chung