On June 18, 2025, the Enlarged Board of Appeal (EBoA) of the European Patent Office (EPO) issued its much-anticipated decision in G1/24 (“Heated Aerosol”) - a landmark ruling that reshapes how patent claims are interpreted at the EPO. The EBoA held that patent claims must always be interpreted in light of the description and drawings, not only when the claim language is ambiguous or unclear (Headnote, reason 18.2). This marks a fundamental shift in EPO practice, bringing it in line with how Article 69 EPC is applied by most national courts in Europe -particularly the Unified Patent Court (UPC) and German courts.
Crucially, the Board found it “a most unattractive proposition that the EPO deliberately adopt a contrary practice” (reason 16), clearly signaling the need for harmonization in European patent law interpretation.
Background: From T 439/22 to a Paradigm Shift
Sparked by a July 2024 referral from Technical Board 3.2.01 (T 439/22), G1/24 addressed whether a claim term’s definition in the description of the patent (in the particular case the term "gathered sheet") can control claim interpretation even if the claim as such is clear on its face and would warrant a different interpretation. The EBoA rejected the more restrictive “claims-only” approach previously taken by decisions such as T 169/20, where reference to the description was permitted only in cases of claim term ambiguity. Instead, the EBoA endorsed a holistic, context-driven interpretation, designed to promote legal certainty and greater consistency across Europe.
Practical Implications: Alignment of Description and Claims Is Now Essential
“The ruling has immediate and far-reaching consequences for applicants and patent professionals”, says Dr. Hannah Jenke, patent attorney at Cohausz & Florack:
- Claims and descriptions must now be tightly aligned during drafting and prosesution.
- Examiners may apply greater scrutiny to claims, assessing them in light of the full specification.
- Third-party challenges could increase, with parties scrutinizing inconsistencies between claims and descriptions.
- Amendments to descriptions - a routine part of prosecution - now requires even more diligence. Misalignment may limit the scope of the claims or trigger objections under Article 123(2) EPC for added subject matter, complicating grant or enforcement.
The oral proceedings, held on March 27, 2025, were livestreamed - underscoring the public importance of this decision and the EPO’s move toward greater transparency in high-stakes legal developments.
Comparative Perspective: EPO, UPC, and German Courts
- UPC: In cases such as NanoString v 10x Genomics the UPC already adopted the same approach as the EPO now in G1/24, i.e. requiring the description to be used for claim interpretation to ensure consistent claim scope across member states.
- German Courts: German judges consistently rely on the description but tend to emphasize the invention’s technical purpose over the claim’s literal wording, leading to a function-oriented claim interpretation. This can lead to broader interpretations than those typically accepted by the EPO’s text-centric approach.
“Despite such nuances, G1/24 enhances predictability and coherence between EPO proceedings and other European courts, particularly the UPC” says Dr. Natalie Kirchhofer, patent attorney and partner at Cohausz & Florack. It represents a significant step toward greater legal harmonization and clarity for patentees and challengers alike across Europe’s patent landscape.
