The Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) handed down its decision in consolidated cases G1/22 and G2/22 on 10 October 2023.
The two cases raised interesting points around entitlement to claim priority i.e., is the EPO competent to assess a party's entitlement to claim priority and, specifically, can party B rely on a priority claim in an application under the Patent Co-operation Treaty (the PCT-application) to a US application filed by party A, where the PCT-application designates party A as applicant for the US and party B as applicant for other jurisdictions. The EBA reached two conclusions. First, that the EPO is competent to assess whether a party is entitled to claim priority under Article 87(1) of the European Patent Convention (EPC), and second, that there is a rebuttable presumption that the applicant claiming priority is entitled to do so. This means that the entitlement to priority is valid unless shown otherwise. This will be good news to patent proprietors as the rebuttable presumption lowers the risk of a priority claim being found to be invalid. On the other hand, this will be less welcome for parties challenging an applicant's right to claim priority, as the rebuttable presumption means that a party must now demonstrate facts which show 'serious doubts' about the applicant's right to claim priority (see para.  of the Decision).
The EBA also concluded that the joint filing of a PCT application by parties A and B (both being applicants for different designated States), claiming priority to an earlier application filed by party A, implies an agreement between A and B which gives B the right to rely on the priority, unless there are substantial factual indications to the contrary. This finding may be particularly relevant to PCT applications claiming priority to an earlier application filed in the US before the introduction of the America Invents Act, which required that inventors be named as applicants in the US (see para.  of the Decision).
The EBA answered questions referred to it in consolidated cases T1513/17 and T2719/19.
T1513/17 concerned an opposition to a European patent claiming priority from a US provisional application filed in the name of the inventors: Rother, Wang and Zhong. A PCT-application was later filed claiming priority to the US provisional application. For the US, the PCT-application names Rother, Wang and Zhong as inventors and applicants. For all other designated states, the PCT-application names Alexion Pharmaceuticals, Inc and the University of Western Ontario as applicants. The EPO granted the application in the name of Alexion Pharmaceuticals, Inc – the University of Westen Ontario having assigned their right to the application to Alexion Pharmaceuticals, Inc during prosecution.
The Opponents asserted that the patent lacked novelty over a number of "intervening publications", i.e., documents published after the filing date of the US provisional application but before the filing date of the PCT-application. The Opponents argued that Alexion was not the applicant or successor in title of the applicants of the priority application.
The Opposition Division held that the priority right was invalid because the transfer of the priority right from the inventors to Alexion was only effective after the filing date of the subsequent application. The claims were therefore anticipated by the intervening publications and lacked novelty.
T2719/19 concerned a European divisional application claiming priority from the same US provisional application as above. The Examining Division held that the priority claim was invalid for the same reasons as laid out in T1513/17, and that the application therefore lacked novelty.
Alexion Pharmaceuticals, Inc appealed both decisions, arguing that the priority right was valid, and that therefore the intermediate publications were irrelevant to validity.
The Technical Board of Appeal (TBA) heard the appeals from the Opposition Division and the Examining Division together. It considered that previous authorities were inconsistent, and therefore referred the following questions to the EBA (as restated by the EBA):
- Is the EPO competent to assess whether a party is entitled to claim priority under Article 87(1) EPC?
- 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 European patent 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?
EPOs competence to assess entitlement to priority
To file a subsequent application claiming priority to an earlier application, an applicant must hold both the right to the subsequent application and the right to claim priority. Before the EPO, these are two distinct rights – the former is governed by national laws, whereas the latter is a right created under the laws of the EPC and the Paris Convention. Since priority rights are governed by the EPC (and, through association, the Paris Convention), the EBA confirmed that the right to claim priority should only be assessed under the laws of the EPC. It therefore concluded that the EPO is competent to assess the right to claim priority.
The EBA went further and concluded that the right to claim priority should be presumed to exist if the applicant claims priority in accordance with Article 88(1) EPC and the corresponding implementing regulations. The finding of this presumption took into account that "i) the priority applicant or its legal predecessor must under normal circumstances be presumed to accept the subsequent applicant's reliance on the priority right, ii) the lack of formal requirements for the transfer of priority rights, and iii) the necessary cooperation of the priority applicant with the subsequent applicant in order to allow the latter to rely on the priority right" (see [para. 105] of the Decision).
The presumption is rebuttable because, in rare circumstances, the priority applicant may have legitimate reasons not to allow the subsequent applicant to rely on the priority e.g., in cases of bad faith behaviour by a subsequent applicant.
This presumption reverses the burden of proof and places it on the party challenging the subsequent applicant's entitlement to priority. This may be difficult in practice, as the evidence required to show an absence of entitlement, such as assignment documents, are often not made public.
As part of the finding that the right to claim priority should be assessed under the laws of the EPC, the EBA considered that it is not necessary for the assignment of priority rights to be in writing, or to be signed by the parties – because such requirements could impose standards higher than those imposed by national laws. The EBA also considered that requiring a transfer of the priority right before the filing of any subsequent applications may be a higher threshold than that imposed by other jurisdictions, and therefore questionable.
Priority of PCT applications
When considering the right to claim priority in the context of PCT applications, the referring decision discussed two approaches: 1) the 'PCT joint applicants approach', and 2) the 'implied agreement approach'.
The 'PCT joint applicants approach' implies that, in a PCT application where A and B are applicants for different states, both applicants may rely on the priority right derived from a priority application filed by only one of the applicants, without the need to transfer the priority right.
On the other hand, the 'implied agreement approach', favoured here by the EBA, assumes that the mutual filing of a PCT application by party A (who also filed a priority application) and party B indicates the existence of an implicit agreement between the two parties conferring the right to claim priority to party B. The EBA stated that this approach applies regardless of whether the subsequently filed application is a PCT application i.e., for the case that the subsequently filed application is a European application if at least one of the co-applicants was an applicant for the priority application.