EPO Enlarged Board clarifies that the description and drawings shall always be consulted to interpret claims

On 18 June 2025, the European Patent Office's Enlarged Board of Appeal issued their keenly awaited G1/24 decision clarifying the rules of interpretation for patent claims when assessing patentability.  The Board decided that the "description and drawings shall always be consulted to interpret the claims" when assessing the patentability of an invention. This is an approach taken by UK and European Courts when assessing infringement and validity and reinforces the value to patentees of having a well written description.

Background

The Enlarged Board of Appeal at the EPO is the highest EPO authority for resolving questions relating to how the EPO should apply the European Patent Convention. One typical way in which the Enlarged Board makes decisions is in response to a Technical Board of Appeal, on reviewing an appeal from a decision taken in examination or opposition proceedings, referring a question in order to ensure uniform application of the law, or if a point of law of fundamental importance arises.

In this case, a Technical Board of Appeal referred three questions to the Enlarged Board, on the basis of a divergence in case law as to whether, and under what conditions, the description may be used to interpret claims when assessing patentability.

The three questions were as follows:

1. Is Article 69(1), second sentence, EPC and Article 1 of the Protocol on the Interpretation of Article 69 EPC to be applied to the interpretation of patent claims when assessing the patentability of an invention under Articles 52 to 57 EPC?
2. May the description and figures be consulted when interpreting the claims to assess patentability and, if so, may this be done generally or only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation?
3. May a definition or similar information on a term used in the claims which is explicitly given in the description be disregarded when interpreting the claims to assess patentability and, if so, under what conditions?

The Enlarged Board considered question 3 inadmissible on the grounds that the referring Board did not need an answer to it in order to reach a decision in their case.

On questions 1 and 2, the Enlarged Board appeared to conclude that, strictly speaking, there was no specific article of the EPC that dealt with the interpretation of patent claims when assessing patentability, but that there was much that could be derived from case law. They also found that the 'description and drawings shall always be consulted to interpret the claims when assessing the patentability of an invention…, and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation'.

Impact

This decision confirms alignment of European Patent Office practice with that of the Unified Patent Court and national Courts and for that reason is welcomed. In our view, a well written description should not be undervalued as it gives the patentee the opportunity to address unforeseen claim interpretations. We expect the European Patent Office to seize on the concluding comments of the Board:

The above considerations highlight the importance of the examining division carrying out a high quality examination of whether a claim fulfils the clarity requirements of Article 84 EPC. The correct response to any unclarity in a claim is amendment.

EPO Board of Appeal Decision G 1/24, Paragraph 20.