The Enlarged Board of Appeal concluded in G 1/24 that the description and drawings must always be consulted when interpreting patent claims for the purpose of assessing patentability. The obvious question left open following that decision was whether definitions in the description could be relied upon to broaden, or narrow, claim scope.
In our follow-up article, we examined the first wave of Appeal Board decisions, post-G 1/24. Those decisions largely concerned attempts by the patentee to use the description to support a narrower interpretation of claim terminology, generally with little success. The emerging message appeared to be that, whilst the description must be consulted, patentees could not rely on it to rescue claims from an otherwise broad interpretation. The opposite question, however, remained open: can the description be used to support a broader interpretation than might arise from a strict reading of the claims alone? A number of recent Board of Appeal decisions have now begun to explore that issue.
T 439/22: broadening a claim term using the description
T 439/22, the decision that ultimately gave rise to the referral leading to G 1/24, concerned the meaning of the term “gathered sheet” in a claim directed to a heated aerosol-generating article. The patent proprietor argued for a narrower interpretation that excluded a spirally wound sheet disclosed in the prior art. The Board instead relied on a broader definition provided in the description and the prior art was deemed to fall within the scope of the claim, thereby rendering the patent invalid.
The Board emphasised that claim interpretation is a unitary or “holistic” exercise, in which the claims and the description are read together from the outset. In doing so, it rejected the distinction drawn in several other post-G 1/24 decisions between merely “consulting” the description and actually “using” it to interpret the claims. For the Board, consulting, referring to, using and taking account of the description were simply different aspects of the same interpretative process.
The Board further stated that a skilled person will ordinarily take an express definition in the description at face value and, provided it is technically reasonable and consistent with the patent as a whole, interpret the claim term accordingly, including “both the broadening and limiting aspects” of that definition (Reasons 3.4 and 6, T 439/22). This is perhaps the clearest indication yet that descriptive definitions can have a substantive broadening impact on claim interpretation.
T 1849/23: broadening an otherwise clear claim term
A similar theme was observed in T 1849/23. The decision considered a claim requiring an angular rate sensor configured to measure a “rate of angular trailer deflection about a hitch pivot point”. The patent proprietor argued that this wording excluded a conventional yaw-rate sensor disclosed in the prior art because the claimed measurement and a yaw-rate measurement are, technically speaking, different quantities. The Board accepted that this interpretation was reasonable when the claim was read in isolation.
However, applying G 1/24, the Board went on to consider the patent as a whole, and noted that the only specific implementation of the claimed angular rate sensor disclosed in the patent was a “gyro” sensor measuring yaw rate, with the description referring to the sensor as a raw angular rate sensor measuring absolute yaw rate. The Board therefore concluded that the claim should not be confined to a strict literal reading when the description is taken into consideration (Reason 1.3, T1849/23), and the claim was found to lack novelty.
T 2043/23: an explanatory use of the description
T 2043/23 illustrates a different application of G 1/24. The decision considered whether claim language directed to a ratio-based comparison also encompassed a mathematically equivalent direct comparison disclosed in the description. The Board concluded that both approaches fell within the scope of the claim. They noted, however, that this case differs from those such as T 439/22, where the description was relied upon to broaden the scope of the claims. In this case, the description served “an explanatory and confirmatory function by assisting the skilled reader in recognising an embodiment already encompassed by the claim wording, without altering the scope of the claim” (Reasons 2.10, T 2043/23).
Final thoughts
The recent application of G 1/24 to broaden claim interpretations suggest that the Boards of Appeal are beginning to develop a relatively consistent approach. It is clear that, whilst the Boards of Appeal have generally been unwilling to rely on the description to import limiting features into claims, they may have greater willingness to use the description to support a broader interpretation of otherwise clear claim language. The practical consequence is that care should be taken during patent drafting and prosecution when including broad definitions in the description, as they may be used to broaden claim scope beyond what was intended and expose the claims to novelty or inventive step attacks.
Matthew O’Farrell
This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.
© Withers & Rogers LLP September 2026
