Seoul Viosys v expert e-Commerce (CoA, UPC_CoA_762/2024, 5 November 2025)

Dhenne Avocats · 10 October 2026

Our analysis

Summary

By decision of 5 November 2025, given in German in the joined appeals UPC_CoA_762/2024 and UPC_CoA_773/2024, the Court of Appeal dismisses Seoul Viosys’ appeal against the Düsseldorf Local Division’s decision of 10 October 2024, which had revoked EP 3 223 320 (a flip-chip light-emitting diode) for added matter over the earlier application and dismissed the infringement action against expert e-Commerce and expert klein. The decision matters to any proprietor whose patent derives from an international application filed in a language other than an EPO official language: the translation the applicant itself filed is presumed accurate, and the proprietor must prove otherwise.

Facts and procedure

Seoul Viosys, supported by Seoul Semiconductor as intervener, sued for infringement in respect of an LED used in a smartphone camera. The defendants counterclaimed for revocation. The patent is a divisional of EP 2 757 598, which itself derives from an international application published in Korean (WO 2013/039344). The Local Division held that claim 1, which covers LEDs with a single mesa, was not disclosed in the earlier application, which described only LEDs with several mesas, revoked the patent and dismissed the infringement action. On appeal, Seoul Viosys filed for the first time a corrected English translation of the Korean publication. The hearing took place on 10 July 2025 in joined proceedings (Rule 302.3).

The applicable law

A patent is revoked if its subject-matter extends beyond the content of the application as filed or of the earlier application (Arts 138(1)(c) and 123(2) EPC). Where the international application is not in an EPO official language, a translation must be filed on entry into the European phase (Art. 153(2) and (4) EPC, Rule 159(1)(a) EPC). Claims are construed under Art. 69 EPC and its Protocol.

Question

Does the earlier application directly and unambiguously disclose an LED with a single mesa, and may the proprietor depart from the translation it filed in order to establish the content of the Korean international application?

Decision

The Court reads “a mesa” as “at least one mesa” (paragraphs 37 to 41) and confirms that added matter is assessed against each earlier application in a divisional chain (paragraphs 44 and 45). It may assess of its own motion how the skilled person understands the earlier application, and the Local Division’s reasoning was no surprise calling for a written reply (paragraphs 49 and 50). Figures 24 to 26 show three mesas, and nothing else in the application clearly discloses a single-mesa LED (paragraphs 51 to 59 and 70 to 80).

On language, the translation filed by the applicant is presumed to reflect the content of the international application accurately. Third parties and the Court may rely on it, and the proprietor must prove any inaccuracy. The corrected translation and the representatives’ submissions were not enough: an expert opinion on the Korean language was expected (paragraphs 60 to 64). Claim 1 therefore extends beyond the content of the earlier application (paragraph 81). As all the auxiliary requests concern single-mesa embodiments, they cannot succeed (paragraph 82), the other invalidity grounds and infringement are not addressed (paragraphs 83 and 84). Seoul Viosys bears the costs of the appeal (paragraph 86).

Key points for practice

• The translation filed on entry into the European phase, far more than a mere formality, in principle determines the content of the international application for the added matter assessment.
• A proprietor challenging its own translation bears the burden of proof and should in practice file a linguistic expert opinion.
• Added matter is assessed against each earlier application in a divisional chain.
• Practical point: the quality of translations of foreign-language international applications should be checked at filing, since any inaccuracy can later be relied on in litigation only on demanding proof.

Provisions applied

Rules of Procedure

Rule 302.3

European Patent Convention

Art. 69, 123(2), 138(1)(c) and 153(2) and (4), Rule 159(1)(a)

Case law cited

NanoString v 10x Genomics, Court of Appeal, 26 February 2024.

Related decisions

• Seoul Viosys v expert e-Commerce, 10 October 2024, the Düsseldorf Local Division decision under appeal.

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.