EPO Enlarged Board of Appeal tackles priority – what you need to know ahead of the hearing

EPO Enlarged Board of Appeal tackles priority – what you need to know ahead of the hearing

It is certainly an exciting time at the EPO – barely a month after the long awaited G2/21 decision, the EPO Enlarged Board of Appeal (EBA) is getting ready to decide on another highly anticipated referral – this time on legal entitlement to priority (G 1/22 and G 2/22). The oral proceedings are scheduled for this Friday (26 May 2023), and a live stream will be available here.
As we previously reported here, the referral concerns both fundamental and specific points of priority entitlement, and the outcome could have far-reaching implications for the assessment of priority entitlement at the EPO.

Referred Questions

To recap, the questions referred to the Enlarged Board are:

I. Does the EPC confer jurisdiction on the EPO to determine whether a party validly claims to be 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:

  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?


Preliminary Opinion

Ahead of the hearing, the EBA issued a preliminary opinion shedding some light on what we can expect to see discussed on Friday.
Firstly, the EBA indicates that they consider both referred questions to be admissible. Therefore unless any of the eligible parties wish to discuss admissibility during the hearing, we can expect the EBA to jump straight to the heart of the matter.
Regarding Q1, the EBA are keeping their cards close to their chest, with no indication of whether they are minded to answer “yes” or “no”. Indeed the preliminary opinion perhaps raises more questions than it answers, with the EBA highlighting five questions they “may consider it useful to discuss”, namely:

  1. Has the case law always been (implicitly or explicitly) supporting the EPO's competence to assess entitlement to priority? (It has been noted in an amicus curiae brief that objections based on the entitlement to priority became routine in opposition proceedings only from about 2010.)

  2. Does Article 60(3) EPC have no impact on the interpretation of Article 87 (implying answering question 1 with "yes") or should the latter be understood in the light of the former (implying answering question 1 with "no")?

  3. Should entitlement to priority be assessed ex officio in examination proceedings?

  4. Could an assessment of entitlement to priority be made on the basis of the autonomous law of the EPC (i.e., without invoking national law)?

  5. If the EPO has the competence to assess entitlement to priority rights, is it also competent to assess the entitlement to the priority application of the respective applicant? (From T 844/18 it can be understood that the entitlement of the party filing the priority application to do so and to acquire a priority right should not be assessed.)

Perhaps it is unsurprising that such a broad question opens new avenues of enquiry, but this certainly  indicates the decision could have a significant and wide-ranging impact. Of course if the EBA were to answer Q1 in the negative, this would reverse current EPO practice, since the EPO does currently assess whether a party is “successor in title” where this is relevant to priority entitlement. Indeed, attacks in opposition based on formal entitlement to priority have massively increased over the last 10 years or so.  Even if the EBA essentially maintains the status quo with an affirmative answer, it seems their ruminations on any of the above five questions are likely to affect a large number of pending cases, as well as potentially opening or closing avenues of attack during opposition proceedings.
Regarding Q2, the EBA was a little less circumspect in their preliminary opinion, indicating that they tend towards answering “yes” to Q2. This would be welcome news to many applicants with PCT applications filed before the America Invents Act.  In such cases, US provisional applications were commonly filed in the name of inventors and inventors were routinely named as applicants for the US only, with no explicit assignment of priority right to the applicant for other states before the PCT filing date. This issue is discussed in detail in our previous article. The EBA suggests that even an informal or implied agreement between PCT applicants regarding the sharing or transfer of the priority right could allow all the PCT applicants to enjoy a priority right, even if said right was only acquired by one of the applicants (by filing the priority application).  In the EBA’s preliminary opinion, even the fact that a PCT application was jointly filed could be considered evidence for such an informal or implied agreement.

What are the parties’ positions?

Finally, it’s interesting to note what the positions of the parties have been in writing:


Proposed answer to question 1

Proposed answer to question 2


Declined to comment directly in writing


Opponent 1



Opponent 2



Notably, the opponents are split on how question 1 should be answered, and all parties are unanimously in favour of the EBA deciding that priority is valid in the Q2 scenario.  No doubt the possible impact of the decision on the wider portfolios of the parties has influenced their positions.
Friday’s hearing will certainly be absorbing, and we look forward to the Enlarged Board weighing in on these critical issues!

Get in touch

If you have questions about a priority claim or a more general query on priority at the EPO, please contact Abi HeathJamie Atkins or your usual Kilburn & Strode advisor.

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