Sean Hutchinson

September 2026

Background

For a long time, the EPO has required applicants to amend the descriptions of their European patent applications to bring these into conformity with the allowed claims before it will grant a European patent. However, in recent years the legal basis for the EPO’s increasingly strict description amendment requirement has been questioned, ultimately causing three questions to be referred to the EPO’s Enlarged Board of Appeal (as case G 1/25). These are:

• If the claims of a European patent are amended during opposition proceedings or opposition-appeal proceedings, and the amendment introduces an inconsistency between the amended claims and the description of the patent, is it necessary, to comply with the requirements of the EPC, to adapt the description to the amended claims so as to remove the inconsistency?

• If the first question is answered in the affirmative, which requirement(s) of the EPC necessitate(s) such an adaptation?

• Would the answer to questions 1 and 2 be different if the claims of a European patent application are amended during examination proceedings or examination-appeal proceedings, and the amendment introduces an inconsistency between the amended claims and the description of the patent application?

The question of whether there is legal basis for the EPO’s description amendment requirement should not be confused with a related yet distinct matter, namely the extent to which the description is to be used to interpret the claim wording. The latter was previously the subject of a separate referral to the Enlarged Board of Appeal (G 1/24), and the decision in that case can be read here. Nonetheless, the framing of the description, and thus answers to the questions referred in G 1/25, arguably became more important after G 1/24 held the description must “always be consulted” when interpreting the claim wording.

The decision in G 1/25 has recently been issued, clarifying both (i) the requirement to ‘consult’ the description when interpreting the claims, and (ii) the extent to which the EPO should require the description to be amended once the claims are allowed. Details of this decision are provided below.

G 1/25: The Correct Interpretation of G 1/24

The Enlarged Board has, in G 1/25, expressly endorsed decision T 439/22 while explaining the requirement to ‘consult’ the description established by G 1/24. This is interesting because the Board in T 439/22 adopted a very different interpretation of G 1/24 to most other Boards of Appeal.

In more detail, the Enlarged Board has held that “claim interpretation is the result of reading the claims, the description and drawings as a unitary process (‘holistic approach’)” (see Reason 7). For the Enlarged Board, “the description and drawings may affect the meaning which the skilled person attributes to the claim wording, but they cannot be used to impose on the claim a limitation or expansion for which the claim wording provides no basis” (see Reason 10).

In other words, G 1/25 confirms the wording of the claims determines the subject matter for which protection is sought. However, that wording must be interpreted according to the skilled person’s understanding of what the proprietor intended it to mean based on a reading of the description, claims, and drawings as a whole. Thus, G 1/25 appears to advocate a change in practice that will bring EPO practice more closely into line with that of the UPC and the national courts of the EPC contracting states (including those of the UK).

G 1/25 also confirms that a definition provided in the description for a term used in the claims is to be attributed to that term when interpreting the claims, provided “the definition is technically reasonable and complies with the overall teaching of the claims, description, and drawings” (see Reason 10). This applies regardless of whether the definition broadens, limits, or otherwise defines the term compared to the ordinary meaning of the term in the art.

The exception for ‘technically unreasonable’ definitions is presumably intended to prevent applicants from misleading third parties who are reading the claims to determine whether the patent is relevant to their FTO, for example by writing in the claim that “the product is black” yet burying in the description a definition that in context “black means white”. Definitions which clarify a term, for example by confirming that “red” means “any colour ranging from pink to brown”, are however now likely to be used when interpreting that term in the context of the claim wording.

Thus, G 1/25 has hopefully settled the debate surrounding the correct interpretation of G 1/24 once and for all.

Description Amendments

The Enlarged Board of Appeal appears to have softened the EPO’s strict stance regarding amendment of the description once the claims have been allowed, holding that “the EPC does not require an adaptation of the description, including any drawings, merely for the sake of formal concordance” (see Reason 22). However, this does not mean the EPO can never require an applicant to amend the description, noting the Enlarged Board held equally that such an amendment may be required to resolve an inconsistency between the claims and the description/drawings which would leave the skilled person reading the application “in real doubt as to the meaning of the claim” (see Reasons 18 and 19).

The Enlarged Board held that such an inconsistency cannot be considered to exist merely because a specific example is included in the description which is not encompassed by the claims (see Reason 20), and that any inconsistency which is not relevant to assessing compliance with the EPC (e.g. novelty or inventive step) need not be rectified.

Instead, the Enlarged Board held an inconsistency must be rectified only if it suggests “an understanding of a claim which is incompatible with the apparent meaning of the claim, and that incompatibility cannot readily be resolved by applying the principles set out” above (see Reason 18). This inconsistency need not necessarily be rectified by amending the description – it could be rectified by amending the claims and/or drawings instead.

Accordingly, in answering the questions referred, the Enlarged Board has held that the answer to Question 1 is “yes”, but only if the inconsistency concerned causes non-compliance with the EPC. The legal basis would then be whichever provision of the EPC is not complied with (the Enlarged Board’s answer to Question 2). The Enlarged Board did not consider the procedural stage a relevant issue, and thus answered Question 3 with “no”.

The points above are brought together in the order at the end of the decision, which recites:

“If the claims of a European patent, or patent application, are amended during proceedings before the departments of the EPO, or in appeal proceedings, and the amendment introduces an inconsistency between the amended claims and the description, including any drawings, of the patent, or application, and because of that inconsistency Articles 52 to 57, 76(1), 83, 84, 123(2) or 123(3) EPC are not complied with, it is necessary to adapt the description, including any drawings, to the amended claims so as to remove that inconsistency.”

Conclusions

G 1/25 brings clarity to two important aspects of European patent practice, and is expected to bring EPO practice more closely into line with that of the UPC and the national courts of the EPC contracting states (including those of the UK).

G 1/25 confirms the claims are to be interpreted in the context of the specification as a whole, i.e. taking into account the description and drawings. The claims are not to be interpreted in isolation and definitions provided in the description for terms used in the claims are to be taken into account, provided they are “technically reasonable” and consistent with the overall teaching of the specification as a whole.

Assuming the EPO adopts the change in practice expected as a result of G 1/25, EPO examiners will now only be able to require applicants to amend the description in specific circumstances. In particular, if when interpreting the claims it becomes apparent that inconsistencies in the specification render the intended claim scope unclear, then an amendment will be required to resolve this. Inconsistencies not relevant to examining compliance with the EPC need not be resolved.

We therefore look forward to seeing how the case law evolves in this area!