G1/25 Referral: EPO to clarify the need to amend the description in line with the claims

A significant referral to the EPO’s Enlarged Board of Appeal reignites debate over description amendments and claim consistency in European patent practice.

On 29 July 2025, the Technical Board of Appeal referred case T 697/22 to the Enlarged Board of Appeal (EBA), marking the first referral of 2025. The case, now designated G1/25 (“Hydroponics”), addresses a fundamental question: must the description of a European patent or application be amended to remove inconsistencies with the claims?

The Case Behind the Referral
The referral stems from opposition proceedings concerning granted patent EP2124521, owned by Knauf Insulation, which claims a hydroponic growing medium comprising an organic binder. During the proceedings, the patentee submitted a key Auxiliary Request 1E, amending claim 1 to specify that the “binder is based on reaction products obtained by curing an aqueous solution comprising citric acid, ammonia and dextrose”.

The Opposition Division issued an interlocutory decision, maintaining the patent based on Auxiliary Request 1E, together with an amended description. Both the Patentee and the Opponent (ROCKWOOL INTERNATIONAL A/S) appealed that decision. The Opponent argued that the amended description was inconsistent with the allowed claims, because features described as optional in the description were now required in the amended claims. The Opponent asserted that the claims do not meet the requirements of Article 84 EPC, which requires claims to be supported by the description.

During the appeal proceedings, the Board of Appeal agreed that the amendment introduced an inconsistency and concluded that the allowability of the request depended entirely on whether such a discrepancy constitutes a legal impediment under the European Patent Convention (EPC).

Questions Referred to the EBA
The Board referred the following questions to the Enlarged Board:

• 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?

Why This Matters?
The referral highlights a clear split in EPO case law, with two opposing underlying principles:

• First line of case law: There is a legal basis that requires the description to be consistent with the amended claims. This has been the more common approach in European patent practice. Decisions supporting this line of case law have either relied on Article 84 EPC alone (e.g. T 24/18) or they have relied on Article 84 EPC in combination with other legal provisions of the EPC (e.g. T 438/22, T 1452/21).
• Second line of case law: There is no legal basis for the refusal of a patent application if there is an inconsistency between any amended claims and the description caused by the claim amendment. A few recent decisions have followed this approach (e.g. T 1989/18, T 56/21), emphasising that neither the EPC nor its Implementing Regulations explicitly require the description to be adapted following claim amendments. These decisions suggest that it is the Applicant’s responsibility to define the subject-matter for which protection is sought, and to bear any consequences arising from an inconsistent description.

The issue has gained greater significance following the EBA’s decision in G1/24, which confirmed that the description and drawings must always be consulted when interpreting claims. This decision brings increased scrutiny to inconsistencies between the claims and the description, as they may directly affect how claims are interpreted and the validity of the patent.

What’s Next?
It is unlikely that the EBA’s decision will be issued until mid-2026 at the earliest. While it is hoped that the decision will provide some clarity on the extent to which it is necessary to amend the description, it is unlikely that G1/25 will completely remove that requirement. At most, it may lead to a more flexible or harmonised approach, with Examiners potentially taking a less rigid stance when requesting amendments. A notice from the European Patent Office dated 4 August 2025 confirms that proceeding before the examining and opposition divisions will not be suspended pending the outcome of the decision, and it is likely that we will continue to see the EPO adopting a strict approach to description amendments for now.

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References:
EPC Guidelines
T697/22 Interlocutory Decision issued on 29 July 2025
G1/24 Decision issued on 18 June 2025
Notice from the European Patent Office dated 4 August 2025