EPO G 1/25: When Must the Description Be Adapted to Amended Claims?

For years, EPO practitioners have disagreed over a deceptively simple question: after the claims are narrowed or otherwise amended, must the description always be rewritten to match? G 1/25 now gives a more precise answer: not merely because an inconsistency exists. Adaptation is required only where that inconsistency has legal significance because it causes non-compliance with the EPC.

Why G 1/25 Matters

On 3 September 2026, the EPO Enlarged Board of Appeal issued G 1/25 (“Hydroponics”), resolving a long-running split in Board of Appeal case law over whether the description must be adapted whenever amended claims become inconsistent with it.

The referral arose from T 697/22. The claims had been amended, and the referring Board considered that the amendment created an inconsistency with passages in the description that defined the relevant binder more broadly. Two lines of case law had developed: one treated adaptation as legally required, often under Article 84 EPC; another held that the EPC contained no general legal basis for forcing the description to mirror narrower claims.

G 1/25 rejects both extremes. The Enlarged Board does not impose a blanket obligation to make the description formally identical to the claims. But it also rejects the idea that the description can simply be ignored when assessing the meaning and clarity of the claims.

The core holding

If a claim amendment introduces an inconsistency with the description or drawings, adaptation is required only where, because of that inconsistency, the application or patent would fail to comply with Articles 52–57, 76(1), 83, 84, 123(2) or 123(3) EPC.

No General Duty of Purely Formal Concordance

One of the most important passages in G 1/25 is what it does not require. Article 84 EPC does not demand purely formal concordance between the description and the wording of the claims. Nor does it create a general obligation to delete every passage, example or embodiment that is not literally reflected in the amended claims.

That matters in practice. For years, description adaptation at the EPO has often become a mechanical exercise: delete or relabel embodiments no longer covered; rewrite “the invention” language; remove claim-like clauses; and make the description track the amended claims as closely as possible. G 1/25 says the legal question is narrower.

The real question is whether the inconsistency changes the legal analysis. If it does not, the EPC does not require amendment merely for tidiness.

But G 1/24 Still Changes the Starting Point

G 1/25 cannot be understood without G 1/24. In G 1/24, the Enlarged Board held that the description and drawings must always be consulted when interpreting claims for the purpose of assessing patentability under Articles 52–57 EPC. G 1/25 expressly builds on that principle.

The Enlarged Board describes claim interpretation as a holistic, unitary process: the skilled person reads the claims, description and drawings together to determine the meaning of the claim language in the context of the application or patent as a whole.

That does not mean the description can rewrite the claim. It cannot impose a limitation—or an expansion—for which the claim wording provides no basis. But definitions and technical teaching in the description can affect the meaning the skilled person attributes to claim terms.

So the practical message is not “stop adapting descriptions.” It is: adapt them for legally relevant inconsistencies, not merely for cosmetic alignment.

What Counts as a Legally Relevant Inconsistency?

G 1/25 says an inconsistency exists where statements in the description or drawings suggest an understanding of a claim that is incompatible with the claim’s apparent meaning, and that incompatibility cannot readily be resolved through normal claim interpretation.

That can matter under Article 84 EPC when it becomes unclear whether information, examples, subject matter or embodiments fall within the scope of the claim. It can also affect patentability under Articles 52–57 EPC if the conflicting description changes how the claim is understood.

The Enlarged Board gives an especially useful inventive-step example: suppose a claim is narrowed to overcome an Article 56 objection, but the description still contains technical teaching corresponding to the broader, pre-amendment claim in a way that undermines the amended claim’s inventive-step position. That inconsistency has legal significance and must be removed.

A Practical Three-Bucket Approach

After G 1/25, description review is easier to structure if passages are put into three buckets.

No conflict: The passage remains compatible with the amended claim. No adaptation issue arises.
Formal mismatch only: The passage is broader, ancillary or no longer claimed, but it does not create uncertainty about claim meaning or EPC compliance. G 1/25 does not impose a general duty to rewrite it merely for concordance.
Legally significant inconsistency: The passage suggests a claim interpretation that conflicts with the amended claim and affects clarity, support, patentability, added matter, extension of protection, or another relevant EPC requirement. Adaptation is required.

This is a more disciplined test than simply asking whether every sentence in the description “matches” the claims.

Definitions in the Description Deserve Special Attention

One reason G 1/25 remains practically important is the Enlarged Board’s treatment of definitions. A skilled person will normally try to take a technically reasonable definition in the description at face value when interpreting a claim term, including both its broadening and limiting aspects.

That means definitions, parameter explanations, functional descriptions and statements about what a term “means” deserve particular scrutiny after claim amendment. They are precisely the passages most likely to affect the interpreted scope of the claim.

For China-origin European applications, this point is especially relevant because Chinese specifications often contain broad definitional language, multiple overlapping embodiments, and drafting formulas that were written before the European claim strategy became clear.

The Same Principle Applies Across EPO Proceedings

The Enlarged Board makes clear that the interpretative role of the description and drawings does not depend on procedural stage. The principles apply in examination, opposition, and the corresponding appeal proceedings.

This is significant because the referral questions were framed separately for opposition and examination. G 1/25 avoids creating two different description-adaptation standards depending on where the case happens to be procedurally.

In appeal, the Enlarged Board also notes that finalising the description during the appeal proceedings remains efficient and often preferable to remitting the case merely for description adaptation.

What Applicants and Practitioners Should Do Differently

Do not treat adaptation as a word-processing exercise. Start with claim interpretation and identify where the description could genuinely change the skilled person’s understanding.
Review definitions first. Defined terms, parameter ranges, “the invention” statements and functional language are high-risk passages.
Check why the claim was amended. If the amendment was needed for novelty, inventive step, clarity or added-matter reasons, ask whether the old description undermines the legal effect of that amendment.
Do not delete useful disclosure unnecessarily. G 1/25 gives applicants a stronger basis to resist purely cosmetic rewriting where no EPC requirement is affected.
Keep G 1/24 in mind. Because the description is always part of claim interpretation, leaving a genuinely conflicting statement in place can have consequences beyond examination housekeeping.
Handle China-to-Europe drafting with the end game in mind. Broad generic language that is harmless at filing may become problematic after the EPO claim set is narrowed.

The Bigger Picture: G 1/24 and G 1/25 Now Work Together

G 1/24 answered one fundamental question: how should an EPO claim be interpreted? The description and drawings are always consulted.

G 1/25 answers the next question: what happens when the claims and description no longer speak with one voice after amendment? The answer is not automatic rewriting. It is targeted adaptation where the inconsistency has a legal effect under the EPC.

For European prosecution, that is a meaningful shift. It reduces the case for mechanical description clean-up while increasing the importance of substantive consistency. The practical task is no longer to make every paragraph look like the claims. It is to ensure that the patent text, read as a whole, supports the legal meaning and validity of the claims that are actually being pursued.