In its decision G 1/24 of June 18, 2025, the Enlarged Board of Appeal of the European Patent Office (EPO) clarified the interpretation of claims. The starting point was a preceding ruling of the Technical Board of Appeal (T439/22).

The decision focused on two questions: Which legal basis (Article 69 EPC and its Protocol or Article 84 EPC) is to be used for claim interpretation in patentability issues, and under what conditions may the description and drawings be used to interpret the claims?

The Enlarged Board of Appeal found that neither Article 69 EPC nor Article 84 EPC alone provide a complete basis. The key clarification is therefore:

1. The claims are the starting point and basis for assessing the patentability of an invention according to Articles 52 to 57 EPC.
2. The description and drawings must always be used to interpret the patent claims. 

For examination, opposition and invalidity proceedings, the decision leads to the description having a relevant impact on the assessment of the patentability of an invention according to Articles 52 to 57 EPC. The assessment of the relevant prior art will be based on the specific definitions and explanations in the description and drawings. Inconsistencies between the claims and the description could thus directly lead to risks in the determination of novelty and inventive step.

This decision may also have implications for patent infringement proceedings in national courts. Although the courts are not legally bound by the EPO's interpretation practice, a uniform and consistent claim interpretation by the EPO should in fact increase legal certainty and reduce the risk of divergent interpretations. In future, courts may follow the EPO's interpretation, thus adapting to the UPC's practice.