Clarifying the role of the description for patent claim interpretation G1/26 “Coated steel strips”
A new referral to the Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) was made on 3 June 2026 in G1/26seeking to clarify the precedent recently set in G1/24. The new referral questions how G1/24’s outcome should be used to assess added matter under Article 123(2) EPC; and more specifically how the description should be used to interpret the breadth of claimed features.
Background
As reported in our earlier legal update, Enlarged Board issues decision in G1/24 ‘Heated Aerosol’, in G1/24 the EBA attempted to address long-standing differing positions on whether the description should be consulted when interpreting claims as part of assessing patentability.
Around one year ago, in G1/24 it was decided that the description and drawings shall always be consulted when interpreting the patentability of the claims (even if the claims are clear).
Since G1/24 there have been various decisions from the Boards of Appeal struggling with how to interpret patent claim scope. For example, in case T2027/23, the Board of Appeal quoted Jacob LJ, European Central Bank v DSS 2008 EWCA Civ 192:
“When validity is challenged, the patentee says his patent is very small: The cat with its fur smoothed down, cuddly and sleepy. But when the patentee goes on the attack, the fur bristles, the cat is twice its size with teeth bared and eyes ablaze”.
And decided that G1/24 does not require the Boards to give the description preference over the wording of the claim. And that, “It is up to a patentee to remedy discrepancies between the description and the claims.”
Context of G1/26
The referral in G1/26 concerns the following claim feature:
“wherein the ratio of titanium to nitrogen is in excess of 3.42”.
Crucially, this claim feature does not specify the units of measurement of the ratio.
The patent proprietor argued that the ratio should be interpreted to be a weight percent, as the description refers to weight percent ratios. On the other hand, the opponent argued that omission of the unit allows the ratio to be interpreted more generally, meaning it could be a molar ratio. Such an interpretation would change the scope of the claim and go beyond the teachings of the specification as filed, resulting in the claim adding matter and the patent being invalid.
As put nicely in the Interlocutory Decision for T 0873.24 – 3.3.05 which makes the G1/26 referral, the case hinges on “the question as to what extent the information found in the description may influence the interpretation of claim 1 and what possible interpretations of the claim need to be originally disclosed”.
The Three Competing Approaches from G1/24
The Board of Appeal (BOA) highlights differing conclusions drawn from G1/24 in caselaw, and applied three different approaches to assess whether the lack of unit in the claim adds matter.
1st Approach: “Consulting the description only to define the skilled person”
Using the first approach, the BOA found that the skilled person would not be able to determine from claim 1 which ratio is intended, meaning the ratio could be a weight percent or a molar ratio; even though a molar ratio is not disclosed in the specification as filed.
As a result, following the 1st approach results in added matter being found.
2nd Approach: “No broadening or limitation of claims based on the patent specification”
Using the second approach, the BOA found that the ratio cannot be interpreted to be relating to a weight ratio, as this purposely restricts the claimed feature in view of the description. Furthermore, the ratio being a molar ratio is compatible with the general technical context of the specification.
As a result of using the second approach, the ratio should be interpreted to be open, which results in added matter being found.
3rd Approach: “Holistic approach permitting broadening and/or narrowing of the interpretation in view of the patent specification”
In the third approach, the ratio would be interpreted in view of the description, meaning it would be interpreted to mean a weight ratio as disclosed in the specification as filed.
As a result, following the 3rd approach results in no added matter being found.
Clearly then, different interpretations of G1/24 are possible, and clarification is needed.
G1/26 Referred Questions
The following questions have been referred to the EBA on how the claims should be interpreted in view of the description:
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?
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?
For completeness, G1/26 also referred Question 1 on the admissibility of referrals to the EBA, which is not related to how claims should be interpreted:
- 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?
Comments
In our report about G1/24 we noted that a key driver behind the G1/24 decision was to harmonise EPO practice with that of national courts and the UPC. We expect that a similar driver applies in the present case. We note that it may be possible to achieve that harmonisation by refusing to admit the referred questions; since there is an argument that G1/24 has already set out how to use the description to interpret the claims (in harmony with the UPC) and that EPO case law simply needs more time to settle down (especially as G1/24 was decided only around one year ago).
We note that question 2 is about granted patent claims; whereas question 3 concerns both patent applications and patents.
We hope a pragmatic way is found to ensure consistent claim scope pre and post grant so that angry cat and sleepy cat interpretations are not selectable at will.
