2.3. Application of the autonomous law of the EPC to the transfer of priority rights

Since the creation, the existence and the effects of priority rights are governed only by the EPC (and by the Paris Convention through its relationship with the EPC), priority rights are autonomous rights under the EPC and should be assessed only in the context of the EPC, regardless of any national laws. Consequently, the entitlement to claim priority (and any related assignments of priority rights) should also be assessed under the autonomous law of the EPC (G 1/22 and G 2/22, OJ 2024, A50, points 83 to 86 of the Reasons). The exclusive application of the autonomous law of the EPC to the transfer of priority rights removes the need for conflict of law rules and the application of national laws, thereby eliminating two main reasons invoked against the EPO’s competence to assess whether a party is entitled to claim priority under Art. 87(1) EPC (G 1/22 and G 2/22, point 130 of the Reasons).

The Enlarged Board endorsed the assessment of priority entitlement under the autonomous law of the EPC but not necessarily all rules discussed in the case law predating G 1/22 and G 2/22 (G 1/22 and G 2/22, point 86 of the Reasons, see also points 68 and 69 of the Reasons citing T 62/05, T 577/11, T 205/14, T 517/14, T 1201/14 and T 1946/21, summarised in this chapter II.D.2.7.). According to the Enlarged Board, the autonomous requirements for the valid transfer of priority rights should not be stricter than national rules applicable to the transfer of priority rights or other property rights. On the contrary, 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. For example, the autonomous law of the EPC should not require that the assignment of priority rights be in writing and/or signed on behalf of the parties to the transaction (see T 62/05, cf. T 205/14 and T 517/14) since this would establish a high threshold in view of the national laws (G 1/22 and G 2/22, points 69 and 100 of the Reasons, see also in this chapter II.D.2.7.3c)).

Even the requirement that the transfer of the right of priority needs to be concluded before the filing of the subsequent European application is questionable in the Enlarged Board’s view (cf. T 577/11 and T 1946/21 reported in this chapter II.D.2.7.4). If there are jurisdictions that allow an ex post ("nunc pro tunc") transfer of priority rights (see the discussion of such transfers under US law in T 1201/14) the EPO should not apply higher standards. However, the allowability of a retroactive transfer of priority rights may have limited practical relevance if priority entitlement is presumed to exist on the date on which priority is claimed for the subsequent European application (G 1/22 and G 2/22, point 100 of the Reasons, see in this chapter II.D.2.4; see also T 2360/19 of 5 March 2024 date: 2024-03-05 in this chapter II.D.2.6).

According to the Enlarged Board, it cannot be excluded that in the context of the rebuttal of the presumption of entitlement to priority, national laws need to be considered as well (G 1/22 and G 2/22, points 111 and 133 of the Reasons; see in this chapter II.D.2.4.1).