EPO Enlarged Board abandons the “only-if-unclear” rule

EPO Enlarged Board abandons the “only-if-unclear” rule –
Description must always guide claim construction (G 1/24)
A friendly nod to the UPC CoA’s NanoString order and Munich LD’s pro-EPO rhetoric

G 1/24 – decision of 18 June 2025

The Enlarged Board of Appeal has now spoken on the long-running “Article 84 vs Article 69” debate. In G 1/24 the Enlarged Board confirms, in unusually direct language, that examiners, opposition divisions and technical boards must always read the claims in the light of the description and drawings when judging novelty and inventive step. Limiting recourse to the specification to cases of linguistic doubt is no longer an option.

With that, the Enlarged Boards close ranks with the UPC:

• The Court of Appeal in NanoString v 10x Genomics (UPC_CoA 335/2023, 26 Feb 2024) held that claims “are not only the starting point but the decisive basis”, yet must be read through the lens of the description and figures.
• Munich LD’s order on inventive step (UPC_CFI 501/2023, 4 Apr 2025) openly urged future UPC panels to stick to the EPO’s problem-solution-approach of the EPO.
• G 1/24 now returns the compliment: it cites the UPC Court of Appeal’s headnote in NanoString as persuasive authority and dismisses the competing line of the Boards of Appeal that looked at the description only when a claim appeared ambiguous in isolation.

What the Enlarged Board decided

Neither Art 69 (+Protocol) nor Art 84 on their own fully explain how to construe claims for patentability. Rather than elevate one over the other, the Enlarged Board distilled two “principles” from decades of case law:

• Claims are the starting point and basis for the Art 52–57 EPC analysis.
• The description/drawings are always consulted, not only upon ambiguity.

Divergence from national courts or the UPC would be “most unattractive”; the EPC’s very purpose is uniformity. On this point, the Enlarged Board agreed with the harmonisation philosophy behind the EPC.

The EBA’s 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.

Why this matters for UPC practice

In two of our latest posts, we covered Munich LD’s insistence that the EPO’s problem-solution-approach should dominate UPC inventive-step analysis as well as the relativism of “closest prior art” in T 2554/22. G 1/24 now embraces the UPC Court of Appeal’s holistic claim construction. The two systems are converging.

UPC judges can comfortably cite G 1/24 when parties argue that the description should be igonred absent “ambiguity”. Practitioners cannot defend a broad, text-only reading in the UPC while pressing a narrow description-driven meaning at the EPO (or vice-versa). Consistency is now mandatory.

Expect EPO examiners and perhaps even UPC divisions to police Art 84 defects more strictly: if a term allows several readings in light of the description, the patentee may be pushed to amend.

Takeaways

• The Enlarged Board dismisses the “only-if-unclear” doctrine: description and drawings are mandatory context for every Art. 52–57 EPC patentability analysis.
• By quoting the UPC’s NanoString order in UPC_CoA_335/2023, the Enlarged Board sends a clear signal of cross-institutional alignment.
• UPC and EPO practice are now converging on two pillars of patent law – claim interpretation and inventive-step assessment.

To the EBA decision  To the UPC CoA decision  To the Blog Overview