CD Paris: Limiting the patent while a revocation action is pending - The impact of EPO limitation proceedings on UPC revocation actions (UPC_CFI_425/2025)

In Chainzone v. SWARCO, Claimant brought a revocation action against a European patent before the CD Paris. Proprietor/Defendant filed a limitation request under Art. 105a EPC while revocation proceedings were pending. The EPO granted the request and published the limited version of the patent in suit before UPC proceedings concluded. 

The CD Paris held that the limited version, not the granted version, of the patent in suit must be taken into account in revocation proceedings. Article 105a(2) EPC, which excludes limitation proceedings while opposition proceedings are pending, does not apply by analogy to revocation proceedings before the UPC. Once published, the limitation of the patent takes retroactive effect under Art. 105b(3), 68 EPC, thus making the limited version the legally relevant one for revocation proceedings.

Although there appears to be limited case law involving initiation of limitation proceedings while nullity proceedings are underway, the approach of the CD Paris appears to be consistent with German patent law. There is (old) case law that limitation proceedings may be conducted in parallel with nullity proceedings (e.g., Federal Court of Justice - “Strahlapparat”, judgement of May 12, 1961, I ZR 37/59). In a  further judgement (“Milchkanne”, judgment of June 14, 1957, I ZR 103/54), the Federal Court of Justice held that, once the limitation decision has been issued, the resulting claim version is decisive in pending second instance nullity proceedings because the limitation takes retroactive effect (see § 64(1) German Patent Act).

The CD Paris dismissed the revocation action and ordered Claimant and the intervening party as the losing parties to bear all costs under Art. 69(1) UPCA. That is, the CD Paris regarded the Proprietor/Defendant as the successful party. This may reflect the CD Paris’ finding that the patent in suit would also have been valid as granted.

It is worth noting that the cost decision may well be open to debate. The proceedings ultimately resulted in the patent being maintained in a more limited form, although the limitation was effected through separate proceedings before the EPO rather than by an amendment request filed with the UPC. Art. 69(2) UPCA allows for a different allocation of costs where a party succeeds only in part or in exceptional circumstances. The relevant consideration should thus arguably be whether and to what extent the limitation narrowed the scope of the patent, rather than whether the patent might also have survived as granted. A similar approach is reflected in Edwards v. Meril, and is also followed by the German courts, for example in Federal Court of Justice, judgement of January 21, 2010, Xa ZR 20/06. 

Here, the limitation deleted only “in particular” from the preamble of claim 1, but the Court did not examine whether or to what extent this narrowed the scope of the claim. Also, no immediate acknowledgment appears to have been made by Proprietor/Defendant. Instead, Proprietor continued to defend the patent as granted and relied on the limited version only after the EPO had granted the limitation request.