G1/25: Patent holders must amend patent specifications – but not in every case

Must the description of a European patent align with amended patent claims? That was the main question confronting the Enlarged Board of Appeal under its president Carl Josefsson in opposition proceedings between Knauf Insulation and Rockwool. Today the judges published their ruling (case ID: G 0001/25). The judges I. Beckedorf, D. Rogers, R. Arnold, E. Chatzikos, G. Pricolo, and R. Bekkering completed the Board ruling over G1/15.

Carl Josefsson © Eva Kubinska

After hearing the case in early June, the seven judges ruled today that “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”.

According to the Enlarged Board, the European Patent Convention does not require purely formal concordance between the claims and the description.

EBA had to settle contradiction

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). The BoA judges concluded at the time 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 had 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 of Appeal then had to 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 EPC provides grounds for this remains disputed. Some recent BoA decisions had diverged from current case law.

Prior to the referral, two lines of case law had developed at the Boards of Appeal. According to the first line, Article 84 EPC provided a legal basis requiring the description to be consistent with amended claims. According to the second line, no such adaptation was necessary, as Article 84 EPC was to be assessed without reference to the description.

Principles of claim interpretation

The Enlarged Board did not endorse the second line of case law. Instead, it confirmed that the principles for claim interpretation established in G 1/24 apply not only to the assessment of patentability under Articles 52 to 57 EPC but also where the assessment of Article 84 EPC requires the meaning of the claims to be determined.

According to the decision, the description and drawings must always be consulted to interpret the claims, not only where a claim appears unclear or ambiguous when read in isolation. Claim interpretation is to be understood as a “holistic approach”, in which the claims, description and drawings are read as a unitary process to determine the meaning that the skilled person attributes to the claim wording in the context of the application or patent as a whole.

However, the Enlarged Board emphasised that the description and drawings may not be used to impose on a claim a limitation or expansion for which the claim wording provides no basis. Where the description contains a definition of a term used in the claim, the skilled person will read the term in that sense, provided the definition is technically reasonable and consistent with the overall teaching.

When adaptation is required

For the purposes of the referral, the Enlarged Board defined an inconsistency between claims and description as existing only where statements in the description or drawings suggest an understanding of a claim that is incompatible with its apparent meaning and where that incompatibility cannot be resolved by applying the principles of claim interpretation. Such an inconsistency may affect compliance with Article 84 EPC where, for example, it leaves unclear whether particular embodiments fall within the scope of the claim.

The Enlarged Board further clarified 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. The approach applies in the same manner in examination, opposition and the corresponding appeal proceedings.

In the dispute between Knauf Insulation and Rockwool, the Boards of Appeal must now implement the guidelines set out by Josefson and his colleagues and make a final decision on the grant of Knauf Insulation’s EP 2 124 521.

Dispute over green tech patent

The patent 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 under the lead of partner Felix Letzelter. However, it was the Danish law firm Inspicos that ultimately represented Rockwool in the proceedings before the Enlarged Board of Appeal. Jakob Pade Frederiksen, Peter Koefoed and Anne Rath Skov-Kjær were responsible on behalf of Rockwool. 

Belgium law firm ARC-IP filed the patent application for Knauf Insulation. Aline Sliwa and Guy Farmer from the Belgian firm were already handling the appeal proceedings and now represented the company in the referal case.