expert klein v Seoul Viosys (CoA, 2 October 2025)

Dhenne Avocats · 10 October 2026

Our analysis

Summary

In a decision of 2 October 2025, given in German in the joined appeals UPC_CoA_764/2024 and UPC_CoA_774/2024, the Court of Appeal sets aside in its entirety the decision of the Düsseldorf Local Division of 10 October 2024. It revokes claims 1, 4, 5, 6 and 9 of Seoul Viosys’ European patent EP 3 926 698 for extending beyond the content of the earlier applications, dismisses all infringement claims and orders the patentee to bear the costs of both instances. The practical interest lies in the added matter test for a patent granted on a divisional application: the comparison must be made with each earlier application, including the original PCT application (paragraphs 64 and 65).

Facts and procedure

Seoul Viosys, supported by the intervener Seoul Semiconductor, sued expert e-Commerce and expert klein for infringement in respect of an LED chip in the camera module of a smartphone they sold. Expert klein counterclaimed for revocation, relying in particular on added matter and lack of inventive step. The Düsseldorf Local Division rejected those attacks and found infringement. Both expert companies appealed. Seoul Viosys sought dismissal and filed auxiliary requests, all confined to single-mesa embodiments. The two appeals were heard together (Rule 302.3 RoP) on 11 July 2025.

The applicable law

The Court construes the claim under Article 69 EPC and its Protocol, with the description and drawings always used as interpretative aids (paragraph 31). There is unallowable added matter where the subject-matter of the granted claim goes beyond what the skilled person derives directly and unambiguously from the application as filed, read as a whole (paragraph 64). For a divisional patent, that test applies to every earlier application (paragraph 65).

Question

Does claim 1, which the parties agree covers single-mesa LEDs, have a direct and unambiguous basis in the parent application, whose claim 1 is directed to an LED with a plurality of mesas?

Decision

The Court holds that it does not. Claim 1 of the parent application expressly concerns an LED with a plurality of mesas (paragraphs 70 and 71). The skilled person would read Figures 24 to 26 as showing one mesa per electrode (paragraphs 75 to 78). The mere theoretical possibility that dicing yields a single-mesa LED, put forward without expert evidence, is not a clear and unambiguous disclosure (paragraph 82). Claim 1 therefore contains added matter (paragraph 84). Even if those figures did show a single mesa, feature 5.2 (openings near the edge of the substrate) is not disclosed there (paragraph 99). The dependent claims fall with claim 1 (paragraph 100). The auxiliary requests, all concerning a single mesa, are not examined, nor are the remaining invalidity attacks or infringement (paragraphs 101 to 103). Seoul Viosys bears the costs of both instances (paragraph 104).

Key points for practice

• For a divisional patent, added matter is assessed against each earlier application, including the PCT application (paragraph 65).
• A feature covered by the granted claim but only theoretically conceivable from the parent application does not meet the requirement of direct and unambiguous disclosure (paragraph 82).
• Arguments already raised at first instance are not excluded as new on appeal under Rule 222.2 RoP (paragraph 62).
• Practical point: auxiliary requests that all retain the feature found to be undisclosed cannot save the patent and are not examined (paragraph 101).

Provisions applied

Rules of Procedure

Rules 222.2 and 302.3

European Patent Convention

Art. 69 and its Protocol, Art. 153(4)

Case law cited

NanoString v 10x Genomics, Court of Appeal, UPC_CoA_335/2023.

Related decisions

• Seoul Viosys v expert klein, 10 October 2024, decision of the Düsseldorf Local Division set aside.

Prepared by Dhenne Avocats from the official decision, consulted on 10 October 2026. The database is updated every week, on Friday. Only the official text is authoritative.