Seoul Viosys v expert klein (CFI, 22 April 2024)

Dhenne Avocats · 10 October 2026

Our analysis

Summary

By an order of 22 April 2024 (UPC_CFI_363/2023, ACT_579244/2023, CC_3580/2024, App_598403/2023, ORD_5343/2024), presiding judge Thomas, acting as judge-rapporteur of the Düsseldorf Local Division, declared admissible the application of Seoul Semiconductor Co., Ltd., parent company and non-exclusive licensee of Seoul Viosys Co., Ltd., to intervene in support of the latter, in the infringement action on EP 3 926 698 B1 against expert e-Commerce GmbH and expert klein GmbH and in the counterclaim for revocation brought by expert klein. The order recognises that a non-exclusive licensee has a legal interest in defending the validity of the patent.

Question

Does a non-exclusive licensee have a legal interest within Rule 313.1 RoP in intervening in support of the patentee, and may its intervention cover the proceedings as a whole?

Decision

The application, lodged before the close of the written procedure and extended to the counterclaim, is admissible (Rule 314.2 RoP). A legal interest requires a direct and present interest in the order sought by the supported party, which rules out a merely derivative interest. Since revocation operates retroactively (Art. 65(2) and (4) UPCA), the non-exclusive licensee would lose its advantage over non-licensees and may therefore intervene to defeat the counterclaim. As the panel decided to hear the action and the counterclaim together (Art. 33(3)(a) UPCA), it must adopt a single interpretation of the patent, so the intervention extends to the whole proceedings. Whether a non-exclusive licence alone would allow intervention in an infringement action was left open. The statement in intervention is due by 6 May 2024, and the order arranges service since the intervener shares the claimant’s representatives.

Key points for practice

• Practical point: a non-exclusive licensee may intervene in support of the patentee against a revocation counterclaim, and joint handling of infringement and validity opens the entire dispute to it.

Provisions applied

Agreement on a Unified Patent Court

Art. 33(3)(a) and Art. 65(2) and (4)

Rules of Procedure

Rules 313.1, 314.2 and 315.1(b)

Case law cited

Court of Appeal, 10 January 2024 (App_584498/2023), Ortovox Sportartikel v Mammut Sports Group, Düsseldorf Local Division, 15 April 2024 (UPC_CFI_16/2024)

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.