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Clarification on the transfer of priority rights expected at the EPO

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Matthias Hoffmann of Maiwald discusses the uncertainty over the transfer of priority rights and the joint applicants approach at the EPO

The transfer of priority rights, especially from applicant-inventors of US provisional applications to their employers, which typically are the sole applicants of the subsequent international application claiming priority at least for most countries, is a matter of dispute in EPO proceedings. Examples of such disputes include decisions T 844/18, T 205/14 and T 1201/14 and pending cases T 2749/18, T 2842/18, T 1837/19 and T 845/19. 

The right to claim priority may be essential for the validity of the patent in the event of relevant prior art in the priority period.

Joint applicants approach

Where there may be doubts over the valid transfer of the priority claim, some applicants/patentees have developed the so-called joint applicants approach to open new possibilities to establish a valid transfer of the priority rights.

In the cases underlying consolidated procedures T 1513/17 and T 2719/19, a Patent Cooperation Treaty (PCT) request identified two companies as applicants for the European patent (EP) territory, whereas the inventors and applicants of the priority application were identified as applicants for the US only. A transfer of priority rights to the new applicants for the EP territory during the priority year as required in the case law (e.g. T 577/11, T 205/14 and T 1201/14) had not been proven.

The board concluded that the validity of a priority transfer was decisive for the patentability of the subject matter disclosed in the subsequent application but had doubts regarding the formal requirements of that transfer and the legal framework of the joint applicants approach relied on by the applicant. Therefore, the board referred the following questions regarding the European Patent Convention (EPC) to the Enlarged Board of Appeal (EBoA) for clarification:

I. Does the EPC confer jurisdiction on the EPO to determine whether a party validly claims to be a successor in title as referred to in Article 87(1)(b) EPC?

II. If question I is answered in the affirmative can a party B validly rely on the priority right claimed in a PCT-application for the purpose of claiming priority rights under Article 87(1) EPC in the case where:

  • A PCT-application designates party A as applicant for the US only and party B as applicant for other designated States, including regional EP protection; and

  • The PCT-application claims priority from an earlier patent application that designates party A as the applicant; and

  • The priority claimed in the PCT-application is in compliance with Article 4 of the Paris Convention?

It appears that question I has been referred merely to settle this issue in the jurisdiction of the boards and first instances at the EPO. Despite the recent decision T 844/18, the competence of the EPO to determine the validity of a priority claim is frequently challenged.

While it appears likely (from the referring decisions and the standing case law) that the EBoA may acknowledge the EPO’s competence to decide on priority questions, referral question II might be subject to intensive discussions and amici curiae briefs.

One major point of discussion may be the integration of the PCT joint-applicants approach into the legal framework of the EPC based on the application of the provisions of Article 118 EPC to the PCT by virtue of the provisions in Article 153(2) EPC and Article 11(3) PCT.

It was held in case T 1933/12 that the applicant of a priority application may share its priority right with a further (joint) applicant in a subsequent EP application without transferring the priority right.

Guidance required

If this ruling applies to the situation underlying the cases in the referring decisions G 1/22 and G 2/22, it may direct countless proceedings before the EPO’s first and second instances in favour of applicants and patent proprietors.

However, it remains to be seen whether this practice will be found to apply to cases in which US applicant-inventors are not identified as applicants for an EP, i.e. the applicants for US and European patents as identified in the PCT request are not identified as joint applicants in the sense of Article 59 EPC. From the referring decisions, it appears that the referring board already casts doubt on this question.

In the alternative and as suggested in the referring board’s decisions, low standards on the formal requirements of a priority transfer under the lex loci protectionis (i.e. the EPC, such as in T 382/07; T 1201/14) over the lex originis (e.g. T 160/13) or the lex domicilii (e.g. T 205/14) may be favoured.

As has been held in decisions of the Court of Appeal in The Hague (case number C/09/51908), the German Federal Court of Justice (BGH X ZR 49/12; Fahrzeugscheibe), the England and Wales Patents Court (case HC09C02624; KCI Licensing and others v Smith & Nephew and others) and other cases, the EPC does not impose any formal requirements on the transfer of priority rights.

Following this approach, the referring board indicates sympathy for the view that the act of filing a PCT application together is sufficient to prove a valid transfer of the priority rights conclusively.

In light of these questions, guidance from the EBoA is required to clarify the requirements for the transfer of priority rights under the EPC. 



Matthias Hoffmann

Patent attorney trainee, Maiwald





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