2.7.2 National laws considered
According to the board in T 577/11, where the applicant of the priority application and the applicant of the subsequent application contractually agree that (only) economic ownership ("economische eigendom" under Dutch law) of the priority application and the right to claim its priority is to be transferred to the subsequent applicant, this is not sufficient to consider the latter a successor in title within the meaning of Art. 87(1) EPC 1973. The board recognised the retroactive effect of the transfer of "economic ownership" but not of the legal title. It concluded that at the time of filing of the subsequent application this arrangement only amounted to a limited transfer, insufficient for the purposes of Art. 87(1) EPC 1973. Furthermore, this case was to be distinguished from the situation of equitable assignment under English law, which was the subject of J 19/87.
In T 160/13 the board confirmed that the opposition division had rightly examined the transfer of the priority right on the basis of German law, which called for a bilateral declaration of transfer by both applicants (§§ 398 and 413 in conjunction with §§ 145 et seq. of the German Civil Code). Such declarations were not subject to any particular formal requirements under German law, and no other requirements of a formal nature could be inferred from the decisions cited by the appellant, T 1056/01 and T 62/05. In the board's view the correspondence on file provided ample proof of the transfer.
In T 205/14, based on the evidence before it, the board was satisfied both that Israeli law did not require an assignment in writing signed by both parties and that the priority right had been transferred to the patent proprietor before the date of filing of the international application underlying the patent in suit. See also T 517/14.
In T 725/14 A was the applicant for the application from which priority was claimed and also the applicant for the parent application of the patent in suit. However, the appellant (opponent) alleged that the priority right had been transferred from A to F (patent proprietor/respondent) by a declaration of assignment dated 1 March 2007 (D17), some days before the parent application was filed. The board rejected the respondent's argument that the transfer was only effective on the date on which a request for registration of the transfer was sent to the EPO (R. 22 EPC; see, similarly, T 404/13). The transfer of the priority right had to be assessed by applying national law (e.g. T 205/14, T 1201/14). The board saw no reason to deviate from the parties' agreed position that the law of the Netherlands was applicable. Referring to a legal opinion filed by the appellant to explain the requirements for assignment of the priority right under the Dutch Civil Code, the board concluded that D17 was sufficient to execute the assignment under the law of the Netherlands. The priority claim was invalid. See also parallel case T 924/15.
See also T 1201/14 in this chapter II.D.2.7.4 on nunc pro tunc assignments under US law and in this chapter II.D.2.3.