Recently, two questions have been referred to the European Patent Office’s Enlarged Board of Appeal regarding the entitlement to claim priority. These arose from two Board of Appeal decisions T1513/17 and T2719/19.

It is well established in the European Patent Convention (Article 87(1) EPC) that the entitlement to claim priority belongs to the applicant of the priority application, or to their successor in title. This means that the applicant for the European patent application must be the same as the applicant for the priority application, unless the rights were transferred before the filing date of the EP application. In cases where the EP application is filed in the name of multiple applicants, priority can still be validly claimed providing that all of the applicants of the priority application are also applicants for the EP application.

In the present case, the European patent application was derived from a PCT application, which claimed priority from an earlier filing. The priority application was filed with the inventors as joint applicants.

The applicant situation on the PCT application was less straightforward. For the ‘US only’ designation of the PCT, the joint applicants were the inventors who were also named as applicants on the priority application. So far, so good. However, for the rest of the designated countries of the PCT application, two new entities were named as the applicant. Thus, the applicants were different for the priority application and the EP ‘part’ of the PCT application. No complete assignment of the right to claim priority by the inventors to the two new entities (before the filing date of the PCT application) was provided. The priority claim was therefore held to be invalid by the Opposition Division.

Before the Appeal Board, the patent proprietor argued that when the applicants for a ‘direct’ (i.e. non-PCT) EP application are different for different designated contracting states, they are regarded as joint applicants for the purpose of proceedings before the European Patent Office. In such cases, the EPO does not investigate the validity of the priority claim. The proprietor argued that the same logic should be applied to an international (PCT) application. This is sometimes known as the ‘joint applicants approach’.

The Board of Appeal considered that the joint applicants concept used in the ‘EP direct’ prosecution might not be directly transferrable to the corresponding PCT routes. One of the reasons for this is that even if a ‘direct EP’ application is considered under the ‘joint applicants approach’, the application undergoes a single prosecution before the EPO. On the other hand, with a PCT application the prosecution is handled separately by regional/national offices. Therefore, the following questions have been referred to the Enlarged Board of Appeal:

  1. 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?
  2. If question 1 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,

  1. A PCT-application designates party A as applicant for the US only and party B as applicant for other designated States including regional European patent protection; and
  2. The PCT-application claims priority from an earlier patent application that designates party A as the applicant; and
  3. The priority claimed in the PCT application is in compliance with Article 4 of the Paris Convention?

The outcome of the referral is likely to have an impact on significant number of prosecution and opposition proceedings.

Clearly, the easiest option for applicants is to obtain assignments of the priority right before a priority claiming application is filed. For those where it is too late, the factual situation is well worth investigating.

If you would like to discuss these issues, please feel free to contact one of our patent attorneys. Otherwise, watch this space as we follow the referral.


Khushbu Solanki

Technical Assistant
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