2.2.2 Applicable law – proof of transfer

In T 844/18 the board held that it was not, as argued by the appellants, the national law of the place of filing of the priority application (here US law) that determined who qualified as "any person", but the Paris Convention, to which the US was a party and which was thus part of the "supreme Law of the Land" (Art. VI, clause 2, US Constitution). The board also concluded that this determination was a purely formal one. The Paris Convention and the EPC provided self-contained definitions of the person claiming priority. This person was defined by the action that they performed, i.e. filing a first application. With regard to the formal requirements for the transfer of the right of priority, the board in T 1201/14 observed that, as the EPC contained neither guidance nor conflict-of-law provisions for that purpose, national law was commonly relied upon by the departments of the EPO entrusted with the procedure. The board also acknowledged that there was no established jurisprudence of the boards as to the national law generally applicable to this question.

In T 1008/96 the European patent application resulting in the patent in suit and the two Italian utility model applications from which priority was claimed had been filed by different persons. The board held that the succession in title had to be proven to its satisfaction. It was a general principle of procedural law that any party claiming a right had to be able to show that it was entitled to that right (see J 19/87). This question had to be answered in accordance with national law. The board concluded that the respondent had failed to prove that it was the successor in title in respect of the two Italian utility model applications. Consequently, no priority rights existed for the patent in suit.

In T 62/05 the board pointed out that the EPC did not contain any regulations on the formal requirements that an assignment of priority rights for the filing of a European patent application should fulfil in order to be considered valid for Art. 87(1) EPC 1973. However, having regard inter alia to the crucial effect that a valid priority date has on patentability (cf. Art. 89 EPC 1973), such transfer of priority rights, in the board's view, had to be proven in a formal way (by analogy with T 1056/01 – also summarised in chapter III.G.4.3.5; see, however, T 160/13 and T 205/14 below). It hence appeared reasonable to apply an equally high standard of proof as that required for the assignment of a European patent application by Art. 72 EPC 1973, which, however, the board concluded was not met here. Furthermore, the appellant could not convince the board that an assignment had taken place implicitly and tacitly before the end of the twelve-month period.

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 ff. of the German Civil Code (BGB)). 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.

The board in T 205/14 pointed out that neither Art. 87 EPC 1973 and Art. 88 EPC nor R. 52 and 53 EPC set out any requirement for determining the law governing transfer of the priority right. It disagreed with the reasoning of T 62/05 (see above) that the transfer had to be proven in a formal way, applying an equally high standard of proof as that required by Art. 72 EPC 1973. Art. 72 EPC 1973 set out formal requirements for a valid assignment of a European patent application and thereby limited the means of giving or obtaining evidence for determining such a transfer. Having regard to Art. 117 EPC and the principle of free evaluation of evidence, the rule should not be extended beyond its scope of application. Art. 72 EPC 1973 constituted harmonised law with respect to the formal requirements for a transfer of a validly filed European patent application, and no reason was apparent for applying it by analogy in the context of a transfer of the priority right preceding a subsequent filing. To do so in view of a subsequent European patent application would, in the case of a European first filing, ignore the fact that the priority right is a right independent of the right to the first application and, in the case of a non-European first filing, that Art. 72 EPC 1973 does not govern the relationship between the applicant of a European patent application and a different applicant of a distinct first application. Art. 72 EPC 1973 and R. 20 EPC 1973, and the related provisions (Art. 60(3) EPC 1973 and Art. 61 EPC), rather defined the conditions under which the EPO may take into account questions of substantive law and procedural acts by a person other than the registered applicant (J 2/01, OJ 2005, 88, point 3 of the Reasons). The board came to the same conclusion as the German Federal Supreme Court in its decision of 16 April 2013 that Art. 87 EPC does not require a formal and separate assignment as provided by Art. 72 EPC.

Furthermore, since the provisions of the EPC did not lend themselves to an autonomous determination of the requirements for transfer of the priority right, the validity of such transfer was a matter of national law (cf. T 1008/96; cf. also approach in T 160/13, J 19/87, T 493/06). In the circumstances of those cases, however, the choice of applicable national law did not seem to be an issue. In none was the law of the state for which protection was sought by the subsequent filing considered to be relevant, nor did they provide guidance on whether the law applicable to the legal relationship between the transferor and the transferee (e.g. corporate agreement, employment contract, or universal succession) should apply, or the law of the state of filing of the first application. This point of law was, however, relevant to the decision in hand. Accordingly, the board considered both the law applicable to the legal relationship between the transferor and the transferee of the priority right and the law of the state of filing of the first application and concluded that the former – in this case the law of the state of the employment relationship between the applicants (inventors) of the US provisional applications from which priority was claimed and the patent proprietor (here the law of Israel) – determined the transfer. On the basis of 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.

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 (see decision Catchword). 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.

Considering the requirement that the right of priority must have been transferred before the filing of the later European application, the board in T 1201/14 took the view that, even if a retroactive transfer such as the nunc pro tunc assignment under US law invoked by the appellant was allowable under US law, it would not be acceptable under Art. 87(1) EPC 1973. The board also held that an implied transfer of a particular right could be accepted when it was sufficiently clear that the parties had formed an agreement and what they had agreed. The burden of proving a valid transfer of the right of priority lay with the proprietor since it was the one claiming that right. As to the standard of proof to be applied, see below.

According to the board in T 1103/15, if a party made statements about conclusions to be drawn on the basis of the applicable national law, it had to file suitable evidence, for example by filing as documents adequate copies of such laws and/or as appropriate by filing as expert evidence the opinions of a suitably qualified lawyer in the relevant jurisdiction (T 74/00).

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; note: 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 applicable law was in general determined by the conflict of laws rules of the court seised, here the board. Such rules were absent in the EPC and the law derived from it. The board saw no reason to deviate from the parties' agreed position that the law of the Netherlands was applicable. The priority application was a European application, was not regulated by any national law and thus did not require the application of any particular national law. All other circumstances pointed to the law of the Netherlands. 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 wording of D17 clearly pointed to the assignment of the priority right to F on 1 March 2007 or earlier. As D17 was intended to provide proof of the assignment of rights, its persuasive weight was considerable. The appellant had discharged its burden of proof. The priority claim was invalid. See also parallel case T 924/15.

On the standard of proof to be applied to an implied transfer of the priority right by virtue of a general policy under German law, the board in T 1201/14 (see above) held that the circumstances of the case in hand required proof "beyond reasonable doubt", as all the relevant evidence lay within the knowledge and power of only one party to the inter partes proceedings. The board in T 2466/13 was in no doubt that the formal transfer of the priority right had taken place, so that there was no need to decide on the standard of proof to be met (see similarly T 2431/17). It nevertheless observed that there was no clear line in the boards' case law on this point: T 205/14 and T 517/14 applied the balance of probabilities, while in T 1201/14, a stricter standard was applied (see above). In T 1786/15, too, the board applied the standard of proof "beyond reasonable doubt". In doing so, it referred to the boards' case law on cases of prior use (in particular T 472/92, OJ 1998, 161) where all the evidence supporting a specific statement of fact was within the power and knowledge of one party (cf. chapter III.G.4.3.2b). However, according to T 407/15, the balance of probabilities was the standard to be applied.

In T 493/06 it was held that the respondents had provided sufficient proof of the assignment of priority rights. In the board's view, even a copy of an assignment agreement could be sufficient provided that evidence was supplied that the content of the copy was identical to that of the original document. Such evidence might, according to board of appeal case law, take the form of an affidavit – even though affidavits were not expressly mentioned in Art. 117(1) EPC 1973 – and the principle of unfettered consideration of the evidence applied to them (see e.g. T 970/93, T 804/94, T 558/95 and T 43/00; also T 535/08).

In T 407/15 the board noted that the two US provisional applications from which priority had been claimed contained a section "Assignee information", identifying the applicant of the current application as assignee. However, it found this not sufficient to establish that the priority rights derived from either application had also been transferred to the applicant. This was a consequence of the fact that the filing of a first application gave rise to two different and independent rights, namely the right to the application in question, and the right of priority. While the aforesaid section appeared to provide evidence of a transfer of the right to a patent, it was silent as to any right of priority based on said filings.

See also the decisions in chapter II.D.4.2.