An opt-out is not a register entry: ownership and procedural choice before the UPC

A mention of an opt-out in the register is reassuring: it is binary, dated and public. Yet it says nothing about two things that decide the fate of a case, namely whether the party who filed the application could dispose of the right, and whether every proprietor consented. The entry is the trace of a procedural act. It is neither the act itself nor evidence that the act produced the intended effect.

The entry is only the trace of an act

For the unitary patent, the register determines ownership. For the European patent, the proprietor is the one who holds the right in substance, and the entry amounts only to a presumption open to rebuttal. The distinction is not theoretical: it governs the admissibility of the action and the validity of theopt-out itself.

The entry is constitutive of the effect of the choice, it is not declaratory of its validity. In other words, the date of entry fixes the moment the choice becomes effective against others, without curing any defect in the application that preceded it.

Two distinct questions

The first is substantive: who could dispose of the right? The answer lies in the deeds of cession, the merger instruments and the instruments of universal transfer, not in an extract from the register. The second is procedural: from when does the choice take effect, and which event may have made it impossible?

That second question is settled by the calendar. Article 83 of the Agreement opens the possibility of withdrawal during the transitional period of seven years, which may be extended, but it is closed if an action has already been brought before the Unified Patent Court, and withdrawal of the opt-out is closed if a national action was commenced during the transitional period.

What the case law has settled

Three decisions hold the field. In Neo Wireless v Toyota of 4 June 2024, the Court of Appeal held that a valid opt-out requires the application of all proprietors of all national parts of the patent: one forgotten co-proprietor is enough to deprive the choice of effect. In AIM Sport v Supponor of 12 November 2024, it held that a national action commenced during the transitional period blocks the withdrawal, the date of commencement being assessed under the procedural law of the State concerned. And in Silimed v Polytech of 7 May 2026, the Hamburg local division recalled that the Registry has no power to review the validity of a withdrawal: an entry may therefore reflect an application that nobody had standing to make.

The remedies available since 2026

The Rules of Procedure now provide an administrative route. Rule 5A, applicable since 1 January 2026, allows an unauthorised entry to be removed by decision of the Registrar, subject to review by the President of the Court of Appeal within one month. Three other rules deserve to be known: Rule 5.2 requires the holder of a supplementary protection certificate distinct from the patent proprietor to join in the application, Rule 5.9 automatically withdraws the opt-out where the patent is granted with unitary effect, and Rule 5.10 prohibits opting out a second time a patent whose opt-out has been withdrawn. That last rule is irreversible, which is enough to make it a matter for management rather than for the filing department.

The audit in five dates

A portfolio is checked through five dates. The date of the opt-out application, with evidence of each proprietor's substantive title. The date of entry, which fixes the effect. The date of any earlier action before the Court. The date of any national action commenced during the transitional period, assessed under local procedural law. And the date, together with the legal character, of every subsequent transfer of ownership, since a judgment on title may have retroactive effect.

The strategic lever is symmetrical. Bringing a national révocation action freezes the opponent's option to withdraw and locks its procedural route. That decision is taken before the writ, not after, and it presupposes that the chain of title is already documented, as we noted in connection with the assignment not entered in the national register. The coordination of the two sets of courts during the transitional period is dealt with in our article on the transitional period.

The decisions cited are tracked one by one in our UPC Litigation Watch. We audit portfolios and conduct these disputes, in particular as correspondent in France for patents and the UPC. Contact us.

This article is an updated adaptation of an analysis by Matthieu Dhenne originally published on Kluwer Patent Blog on 15 September 2026: An Opt-Out Is Not a Register Entry: Ownership and the Limits of Procedural Choice Before the UPC. Official source: Agreement on a Unified Patent Court, Article 83, OJ C 175 of 20 June 2013.