G1/25: EBA to decide on hydroponic case between Knauf and Rockwool

Must the description of a European patent align with amended patent claims? The EPO’s Enlarged Board of Appeal must now address this question. At the end of July, Technical Board of Appeal 3.3.02 under chairman O. Müller referred several questions to the EPO’s highest judicial instance in the dispute between Rockwool and Knauf Insulation (case ID: T 697/22).

In the referral, the BoA judges cite Article 112(1)(a) of the European Patent Convention. They deem it necessary to harmonise EPC law on the following issues:

1. 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?
2. If the first question is answered in the affirmative, which requirement(s) of the EPC necessitate(s) such an adaptation?
3. 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?

Dispute over green tech patent

The case concerns Knauf Insulation’s EP 2 124 521, which covers a hydroponic growing medium. Knauf Insulation manufactures insulation materials primarily used in buildings, including those for green roofs and facades. As global warming concerns mount, the greening of buildings is seen as innovative technology for reducing overheating in buildings and urban areas.

Rockwool, active in the same segment, opposed the grant of Knauf’s EP 521 with support from Meissner Bolte. The Meissner Bolte team includes partner Felix Letzelter, as well as Klaus Linn and former BoA judge Hans-Peter Felgenhauer.

Belgium law firm ARC-IP filed the patent application for Knauf Insulation. Aline Sliwa and Guy Farmer from the Belgian firm are handling the appeal proceedings.

EBA must settle contradiction

The BoA judges concluded that Knauf’s auxiliary request claim version is patentable. However, Knauf Insulation had not adapted the description, which the Opposition Division had already criticised. Both Knauf and Rockwool appealed the Opposition Division’s decision.

Knauf’s auxiliary requests created a contradiction between the claims and applicable description. Knauf Insulation submitted an amended description during appeal proceedings, but the BoA judges rejected this as late. The Enlarged Board must now decide whether these contradictions prevent EP 521’s grant.

Based on previous BoA case law, experts say, the EPO typically requires patent descriptions to align with amended claims. However, whether the European Patent Convention provides grounds for this remains disputed. Some recent BoA decisions have diverged from current case law.

Wide-reaching implications

Experts had anticipated the EBA referral and view its potential consequences as significant.

“Just in one of its most recent cases, G1/24, the EPO’s Enlarged Board of Appeal had decided that the description should always be consulted when interpreting claims. This underscores the importance of G1/25 and the description amendments at issue there. The outcome of G1/25 which can be expected in 2026 will be pivotal for patent applicants and practitioners,” writes Cohausz & Florack on its website.

Meanwhile, Boehmert & Boehmert notes that “the decision significantly affects applicants, as adapting descriptions after claim amendments requires considerable effort and cost. Such amendments risk negatively impacting subsequent national court interpretations or restricting freedom to act in validity proceedings”.

UK law firm Venner Shipley writes,”The EPO is currently the only patent office that considers it necessary for patent quality or legal certainty that the detailed description is amended to align with the claims. While many applicants and patent professionals would welcome a relaxation of the EPO’s requirements, it is by no means certain that the EBoA will give a clear and definitive answer…. .”