The EPO’s Enlarged Board of Appeal (EBA) has changed the law of ‘formal’ or ‘legal’ priority (G 1/22 and G 2/22, October 10 2023). There is now a rebuttable presumption that the priority right is valid.
The reason for a rebuttable presumption is founded on the fact that there are no formal requirements for the transfer of priority rights as well as the presumed common interest of the priority applicant and the subsequent applicant, who must cooperate for priority to be invoked. Therefore, as long as the formal requirements under Article 88(1) of the European Patent Convention for claiming priority have been met (which require the priority applicant to cooperate with the subsequent applicant), the rebuttal presumption will arise.
The rebuttal presumption will apply to any case in which the subsequent applicant is not identical with the priority applicant, including in the case of a plurality of co-applicants of the priority application. For jointly filed – i.e., European patent or Patent Cooperation Treaty (PCT) – applications in which one of the co-applicants is also the priority applicant, the EPO will deem an implicit agreement between the co-applicants.
Although validity of the priority right can still be challenged by third parties in opposition proceedings, the burden of proof is on the challenger, with the presumption rebutted in “rare exceptional cases”. Two examples of “rare exceptional cases” were provided by the EBA; not related to transfer of the priority right, but instead whether “the priority applicant may have legitimate reasons not to allow the subsequent applicant to rely on the priority”. The examples were:
“Bad faith behaviour on the side of the subsequent applicant”; or
“The outcome of other proceedings such as litigation before national courts about the title to the subsequent application”.
Challengers of the priority right are not disadvantaged, as “even if a ‘wrong applicant’ claims priority for its subsequent application, this does not necessarily mean that the priority right cannot be relied on”. The EBA then provided the example of a ‘wrong applicant’ claiming priority, followed by national entitlement proceedings, with the result that the ‘rightful applicant’ is then able to file a divisional application for the same subject matter claiming the same priority date. The EBA concluded that: “In view of legal certainty, it should thus be considered that there is always a party who is entitled to claim priority – even if this party must be determined in national proceedings.”
The EBA noted that transfer or assignment of priority may have limited relevance given the new rebuttal presumption, while doing away with requiring written assignments from the priority applicants: “The EPO should adapt itself to the lowest standards established under national laws and accept informal or tacit transfers of priority rights under almost any circumstances”.
Impact of G 1/22 and G 2/22 already being felt
On November 28 2023, the German Federal Court of Justice embraced the decision of G 1/22 and G 2/22, adopting the presumption of valid priority into German law. In X ZR 83/21 (Sorafenib-Tosylat), the court held that despite only a portion of priority assignments from 18 priority applicants having been submitted, the priority right was held valid. The presumption was not rebutted and the patentee was not required to provide evidence of the ‘missing’ assignments. The court found that the other priority applicants consented implicitly, no written agreement being necessary. The court further held that there was an implied agreement between the applicants given the 18 priority applicants were also named on the PCT application as applicants for the US.
This decision suggests that other national courts will similarly follow the decision of the EBA in G 1/22 and G 2/22 and those wishing to challenge the validity of a patent will need to assume priority is valid when evaluating their chance of success.
