By: John Richards
In its decision of September 3, 2026 in case G1/25, the Enlarged Board of Appeal of the European Patent Office clarified the situations in which amendment of the specification to conform with claims that had been amended during examination or opposition proceedings. It held that amendment to the description was necessary when the amendment to the claims led to a “discrepancy” between the claims and the description or drawings that resulted in a failure of the application to comply with any of the European Patent Conventions requirements for any of the following: novelty or inventive step (Articles 52 – 57), that any divisional application did not extend beyond the content of its parent (Article 76), that the application provided a sufficiently clear and complete disclosure of the invention (Article 83), that the claims are clear and concise and supported by the description (Article 84), and that the amendments did not extend the subject matter of the application as filed or, in the case of a granted patent broaden the protection that the patent affords (Article 123). However, as noted below, amendment would be necessary where apparent discrepancies could not be resolved by proper claim construction so that they resulted in real doubt as to the meaning of a claim.
Background
It has for many years been the practice of both the Examining Divisions and the Opposition Divisions of the European Patent Office to require the applicant or patent owner of a patent that survived opposition to amend the specification to conform to the final form of claims that were allowed after examination or those that were upheld after opposition. This was said to be required to provide clarity as required by Article 84 EPC and Rule 42 of the Implementing Rules. Many practitioners have viewed this as inconsistent with international practice and as generating an unnecessary expense and challenges started to be made to the legal basis for the EPO’s practice.
In its decision in Case T1989/18 of December 16, 2021 an appeal board concluded that neither Article 84 of the European Patent Convention nor Rule 42 of the Implementing Rules provided a basis for requiring an amendment of the specification to conform with the final form of the claims as long as the claims were clear in themselves.
Decision T2194/19 of October 24, 2022, a board of appeal held that compliance with the European Patent Convention did not necessarily mean that the description had to be amended to delete reference to embodiments that no longer fell within the scope of an independent claim.
In the early 2020s other appeal boards expressed similar view that as long as the scope of the claims was clear in itself when read with normal skills, amendment of the specification would not be necessary.
Then on 26 February 2024 the Court of Appeal of the European Unified Patent Court in NanoString Technologies -v- 10x Genomics, held that for questions of both infringement and validity:
The patent claim is not only the starting point, but the decisive basis for determining the protective scope of a European patent under Art. 69 EPC in conjunction with the Protocol on the Interpretation of Art. 69 EPC. The interpretation of a patent claim does not depend solely on the strict, literal meaning of the wording used. Rather, the description and the drawings must always be used as explanatory aids for the interpretation of the patent claim and not only to resolve any ambiguities in the patent claim. This does not mean that the patent claim merely serves as a guideline but that its subject matter also extends to what, after examination of the description and drawings, appears to be the subject-matter for which the patent proprietor seeks protection. The patent claim is to be interpreted from the point of view of a person skilled in the art.
The EPO Appeal Board decisions noted above had discounted the role of Article 69 of the European Patent Convention when considering the question of consistency between the wording of the claims and the description on the basis that they believed Article 69 applied only to how a claim was to be interpreted in the context of an allegation of infringement.
The Unified Patent Court decision was soon followed by a decision of the Enlarged Board of Appeals of the European Patent Office on June 18, 2025 in Case G1/2024. Noting the desirability of consistency in interpretation of the law between the agency granting patents (the EPO) and the court that would handle litigation on a large percentage of the patents so granted (the Unified Patent Court), the Enlarged Board held:
The claims are the starting point and the basis for assessing the patentability of an invention under Articles 52 to 57 EPC. The description and drawings shall always be consulted to interpret the claims when assessing the patentability of an invention under Articles 52 to 57 EPC, and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation.
The stage was then set for Case G1/25.
The Decision in Case G1/25
After concluding that prior appeal board decisions noted above holding that if the claim language was clear there was no longer any reason to consider the consistency with the description could not survive as good law following the Enlarged Board’s decision in G1/2024, the Enlarged Board went on to consider the circumstances in which amendment of the description or drawings might be necessary after claims had been amended.
After noting that there was no specific legal provision in the EPC that necessarily required description amendments, the Enlarged Board continued
It follows that the necessity to adapt the description or any drawings is not a consequence of the existence of an inconsistency as such, but arises only where, and to the extent that, the inconsistency has legal significance because it leads to noncompliance with a requirement of the EPC.”
Because the description, drawings and claims were to be read following a holistic approach, an “inconsistency” between the description and claims would require amendment if that inconsistency resulted in the application or patent failing to meet any of several requirements of the European Patent Convention.
In giving guidance as to what constitutes an “inconsistency” the Enlarged Board stated that it considered that an inconsistency between the claims and the description exists only where one or more statements in the description, including any drawings, suggest an understanding of a claim that is incompatible with its apparent meaning and that incompatibility cannot readily be resolved by applying principles of claim interpretation. The Board noted:
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. In line with this approach, a person skilled in the art reading the claim in the context of the description and drawings will try to take a definition found in the description at face value. As long as the definition is technically reasonable and complies with the overall teaching of the claims, description and drawings, the skilled person will read terms in the claim in the sense of the definition, taking into account both the broadening and limiting aspects (see T 439/22 of 11 December 2025, points 3.4 and 6 of the Reasons).
The Enlarged Board noted:
In many cases, what may appear at first to be such an incompatibility can be resolved without difficulty by applying the principles for claim interpretation set out in G 1/24. If the person skilled in the art reading the claim in the light of the description and any drawings would be left in real doubt as to the meaning of the claim, however, there is an inconsistency. An inconsistency is not established merely because the description, including any drawings, contains a technical teaching, examples, or embodiments that do not fall within the claimed subject-matter. If, on the other hand, due to such an incompatibility, it is unclear whether a technical teaching, examples, or embodiments do, or do not fall within the claimed subject matter, an inconsistency exists. Where the description, including any drawings, contains statements that are inconsistent with the claims in the sense defined above, and that inconsistency leads to non-compliance with one or more requirements of the EPC, the patent (or application) can comply with the EPC only if that inconsistency is removed (or neutralised), either by amending the claims, amending the description and/or the drawings, or both. Conversely, where an inconsistency between the claims and the description, including any drawings, is not such as to be relevant for the assessment under the EPC, such an inconsistency need not be removed (or neutralised). The EPC does not require an adaptation of the description, including any drawings, merely for the sake of formal concordance.
The Enlarged Board further stated that this approach is not contingent on the existence of amendments to the claims, but reflects general principles governing the determination of the meaning of the claims under the EPC.
Conclusion
Although the decision recognizes the role of the skilled reader in determining whether there is a true inconsistency between the meaning of the claims and the wording of the specification such that it may no longer be necessary to amend or delete language that clearly does not affect the meaning of the claims, it seems that the decision still leaves scope for continuing requirements for amendments to the description from examiners.