Europees Octrooibureau, 10-10-2023, nr. G 0001/22

Question I (‘Does the EPC confer jurisdiction on the EPO to determine whether a party validly claims to be a successor in title as referred to in Article 87(1)(b) EPC?’) refers to Article 87(1)(b) EPC only, where reference is made to priority filings in or for Members of the World Trade Organisation. Article 87(1)(a) EPC refers to priority filings in or for States party to the Paris Convention. The ‘successor in title’ passage in Article 87(1) EPC is not specific to one of the groups of states referred to in Article 87(1)(a) and (b) EPC. These groups overlap to a large extent, and the legal issues are the same for both groups. Moreover, question II refers to ‘claiming priority rights under Article 87(1) EPC’. It is therefore assumed that the reference to sub-paragraph (b) of Article 87(1) EPC in question I is of no relevance.

The wording of question I with respect to the jurisdiction of the EPO is clear in that it addresses the competence of the EPO (i.e. of the examining and opposition divisions and also the boards of appeal) to assess the entitlement to claim priority of the party filing the subsequent application.

There may be uncertainties about the entitlement to claim priority under Article 87(1) EPC also in cases where not the succession in title but the identity of the person having filed the priority application is in dispute. In T 844/18, concerning a situation where four inventors were applicants of the priority application and only three of them filed the subsequent European application and claimed priority, the board took the position that succession in title was not an issue in this case (see Reasons, point 21). In the Reasons (point 9 and 23) of T 844/18, reference is made to the jurisdiction to examine ‘who is entitled to the right of priority’ (Reasons, points 9 and 23). The discussion of the EPO's jurisdiction in T 844/18 consequently encompasses the determination of both the person who filed the priority application and its successor in title. Similar to the facts underlying T 844/18, a legal entity consisting of a plurality of persons or entities (such as a partnership) may be the applicant of a priority application, and the same entity with a changed composition or membership may claim priority from this application. In such situations, it may be difficult to distinguish between the determination of the personal identity between the two applicant entities and the assessment of a succession in title.

To cover all situations where the right of an applicant to claim priority is relevant in proceedings before the EPO, question I is rephrased as follows: ‘Is the EPO competent to assess whether a party is entitled to claim priority under Article 87(1) EPC?’. As explained in the communication of the Enlarged Board of 21 March 2023, question I refers to the EPO's competence to assess the entitlement to claim priority for the subsequent application and it encompasses all situations where the applicant claiming priority for its subsequent application is not clearly identical with the applicant of the priority application.

As has long been pointed out in the discussions on entitlement to priority, the issue of entitlement not only arises with respect to a patent or patent application examined or opposed to in proceedings before the EPO. The issue equally arises with respect to prior art, namely patent documents forming prior art under Article 54(3) EPC and relying on a priority date prior to the effective date of the European patent application or European patent under consideration (see e.g. T 493/06, Reasons, points 1 to 11; T 382/07, Reasons, point 9). Question I is understood to cover both cases; the objection that an applicant was not entitled to claim priority can equally be raised by an opponent (if the priority issue concerns the opposed patent) or by a patent proprietor (if the priority issue concerns a prior art document).

Question II is understood to concern proceedings before any instance or department of the EPO where the situation described in question II occurs. According to the referring decision, the question needs to be answered only ‘[i]f question I is answered in the affirmative’.

The question covers a special situation occurring where a party, typically the inventor(s), files a US priority application (also in the form of a provisional application) which is then used as priority application for a later PCT application designating one party (typically still the inventor(s)) for the US only and another party (typically the employer of the inventor(s)) for regional European patent protection. Before the ‘America Invents Act’ (AIA) of 2011 entered into force, only the inventor(s) could be applicants in a US patent application (see e.g. Druschel/Kommer, Die formelle Priorität europäischer Patente, GRUR 2022, 353). The priority application underlying the present referral (filed in 2004) had to be filed by the inventors under the then applying laws.

As implied by the referring decision (see Reasons, point 43), the wording of question II is addressing the facts underlying the referral and the ‘PCT joint applicants approach’ (see above point 11) in a general way but it is not to be understood as being further limited to specific factual circumstances (e.g. to a number of parties).

As pointed out in the referring decision (Reasons, point 18), confusion should be avoided between the ‘PCT joint applicants approach’ mentioned above and the ‘all applicants approach’ used, for example, in decision T 844/18 (Facts and Submissions, point VIII). In this case, four inventors were applicants of the priority application and only three of them filed the subsequent PCT application (encompassing the European application) and claimed priority. The priority claim failed to meet the requirement that all applicants of the priority application must also be applicants of the subsequent PCT application for which the priority is claimed.

The referring decision critically summarises various possible legal bases for the ‘PCT joint applicants approach’ (Reasons, points 28 to 39). However, the referring board did not limit its question II to the viability of the ‘PCT joint applicants approach’, thereby leaving open the possibility that question II could be answered in the affirmative with another reasoning (for example, by acknowledging that the joint filing of a PCT application is sufficient proof for the validity of the priority claim).

As far as the reference to Article 4 of the Paris Convention at the end of question II is concerned, it is understood that this refers to compliance with all provisions of Article 4 Paris Convention except for the entitlement to priority as addressed in Article 4A(1) Paris Convention (see above point 30).

The referring decision addresses the conflict of laws rules applicable to the transfer of priority rights, noting that a separate question was not necessary ‘because it is inherently contained in the questions posed and it will be addressed in the considerations of the EBA, as needed’ (Reasons, point 37).

According to Article 112(1)(a) EPC, ‘[i]n order to ensure uniform application of the law, or if a point of law of fundamental importance arises’, a board of appeal ‘shall, during proceedings on a case and either of its own motion or following a request from a party to the appeal, refer any question to the Enlarged Board of Appeal if it considers that a decision is required for the above purposes.’

The Enlarged Board must examine the above admissibility requirements with respect to each referred question individually (G 1/19, OJ EPO 2021, A77, Reasons, point 56, with further references).

Since the Enlarged Board takes the position that question II should be admitted (see below points 49 ff), question I should also be admitted for the sole reason that the questions are interlinked insofar as an affirmative answer to question I is a precondition for approaching question II. However, question I in itself already fulfils the requirement of Article 112(1) EPC that an answer is required to ensure uniform application of the law or because a point of law of fundamental importance arises.

The issue of entitlement to priority arises with every patent application for which priority from an earlier application is claimed or which is confronted with prior art patent documents claiming priority. Where priority entitlement is disputed in any proceedings, the EPO instance addressing the issue must (at least implicitly) decide on question I. The question — or an affirmative answer thereto — thus can be viewed as fundamental for any investigation of priority entitlement under Article 87(1) EPC. The discussion concerning question I in the present referral proceedings shows that fundamental questions of law are touched upon, such as the extent of the EPO's jurisdiction for questions of civil law or the right of a third party to challenge entitlement to priority rights to which the third party cannot claim any entitlement.

It has been argued in certain amicus curiae briefs (Vossius & Partner and Grund IP Group) that question I should not be admitted because there was no conflicting case law on the issue of the EPO's jurisdiction. However, diverging decisions are not a requirement for the admissibility of a referral if a board is referring a question to the Enlarged Board (Article 112(1)(a) EPC). Regardless of whether or not any decisions are in direct conflict with e.g. T 844/18, the EPO's jurisdiction concerning the entitlement to the priority right has been questioned by boards of appeal in several cases (see the referring decision, Reasons, point 26), and the issue is arising in various other cases before different boards. The condition that an answer of the EPO is required to ensure uniform application of the law is therefore met.

The Enlarged Board is satisfied that both of the alternative conditions of Article 112(1)(a) EPC are met (point of law of fundamental importance and necessity to ensure uniform application of the law). The condition that an answer to question 1 is needed for the referring board to decide is met because an answer is needed to question II (above point 45). For these reasons, referred question I is admissible.

Question II mirrors the facts underlying the referring decision (see above point 38). An answer to question II is therefore required for the referring board to decide in the two pending appeal cases.

As described above (point 37), question II concerns a specific situation related to US law where only inventor(s) could file a patent application. This requirement has ceased to exist. However, apart from the two cases underlying this referral, there are still a significant number of cases pending where the application was filed while only inventors could apply for a US patent (see e.g. case T 419/16, where an interlocutory decision was taken on 3 February 2022 to stay the appeal proceedings until a decision is issued in the present referral). Moreover, inventors still act as applicants for the US only in cases where the PCT application is filed both for the US and for protection in Europe under the EPC.

While the question refers to a specific situation, the answer would not necessarily be limited to the viability of the ‘PCT joint applicants approach’ and it may cover other situations where the applicant's entitlement to the priority right is challenged. However, even if the answer covered only the situations described in question II, the question is considered to touch a point of law of fundamental importance in the terms of Article 112(1) EPC.

The Enlarged Board is not aware of any case law challenging the viability of the ‘PCT joint applicants approach’. However, it is noted that the possible legal bases for this concept have been questioned even in the referring decision (Reasons, points 28 to 33). The fact that there are different legal bases proposed for the ‘PCT joint applicants’ approach already shows that there is no uniform approach to this concept. Moreover, decisions of national courts (see Reasons of the referring decision, points 40 and 41) and various amicus curiae briefs base their positions supporting an applicant's right to priority on other arguments than the ‘PCT joint applicants approach’ (see above point 24). In view of future case law, it is desirable that not only the answer to question II is uniform but also the basic reasoning behind such answer.

Since an answer to question II is necessary for the referring board to decide the pending appeal cases and at least the criterion of ‘a point of law of fundamental importance’ under Article 112(1)(a) is met, question II is admissible.

The basic purpose of the right of priority is to safeguard, for a limited period, the interests of patent applicants in their endeavour to obtain international protection for their inventions, thereby alleviating the negative consequences of the principle of territoriality in patent law (T 15/01, OJ EPO 2006, 153, Reasons, point 32, with references to the relevant literature). The priority provisions contained in the Paris Convention should not be regarded as a body of exception clauses which should be interpreted strictly (see in this respect T 998/99, OJ EPO 2005, 229, Reasons, point 3.1; see also T 1201/14, Reasons, point 3.2.1.3). To the contrary, the Rules of the Paris Convention and the self-contained priority system of the EPC should be construed in a manner which ensures that the above-mentioned general purpose is fulfilled as far as possible (T 15/01, Reasons, point 34, confirmed in T 5/05, Reasons, point 4.4; see also Straus, The Right to Priority in Article 4A(1) of the Paris Convention and Article 87(1) of the European Patent Convention, JIPLP 2019, 687, 688/689).

For the person filing a patent application in a state addressed in Article 87(1) EPC, the priority system means that it has the option to file a bundle of subsequent applications for the same invention in a freely selected group of other territories where each of the later (national or regional) applications may benefit from the priority date of the first application. The priority period of twelve months on the one hand allows for an evaluation by the applicant as to where patent protection should be sought. On the other hand, the clear limitation of the period provides legal certainty to third parties who ought to know the geographical limitations of the patent protection they may be confronted with.

The effect of the priority right (namely, the exclusion of intermediate prior art; see above point 26) often concerns publications originating from the priority applicant or persons connected with it. The priority right thus also protects an applicant from its own intermediate prior art and allows it to publish the content of the priority application before the subsequent applications are filed. This aspect is of particular relevance in a patent system like the European patent system that generally does not provide grace periods prior to filing a patent application during which publications of the applicant are non-prejudicial.

Only the subsequent application (for which priority is claimed) and the respective applicant may benefit from the priority right. For the priority application, the priority right derived therefrom is irrelevant since for the priority application there is no period between the priority date and the application date (and, consequently, no intermediate prior art).

If questions of entitlement to claim priority under Article 87(1) EPC arise in national proceedings, the court seised needs to address all issues concerning the applicant's identity or succession, including the determination and application of foreign laws. However, in proceedings before national courts, conflict of laws issues and the related application of foreign law tend to cause less concern than in proceedings before the EPO. On the one hand, national courts can rely on their applicable conflict of laws rules and the respective case law. On the other hand, the domestic (substantive) laws of the national court are often applicable, either because the applicable conflict of laws rules refer to it or because conflict of laws issues are not relevant in cases not having connections to more than one jurisdiction.

If the facts of a case involve one or more jurisdictions other than the court's own jurisdiction, the court's set of conflict of laws rules is applied by first qualifying the legal relationship at issue in view of the individual conflict of laws rule that may be applicable. Specific statutory conflict of laws rules for the transfer of priority rights do generally not exist in national legislations on private international law. German courts have found, for example, that the validity of the transfer of a right to claim priority is subject to the laws of the state of the priority application (lex originis) while the obligations between the assignor and the assignee are subject to the laws applicable to the contractual relationship between these parties (lex contractus) (see the summary in German Federal Court of Justice X ZR 14/17 — Drahtloses Kommunikationsnetz, point 68).

The referring decision (in Reasons, point 40) cited another decision of the German Federal Court of Justice (Bundesgerichtshof, BGH) where the German conflict of laws rules, including the Rome I Regulation (see below point 80) pointed to the applicability of German law, which did not require any particular formalities for the transfer of priority rights. In view of the relationship between the parties to the transfer and a research and development agreement concluded between them, the German Federal Court of Justice accepted that there was an implicit agreement (‘konkludente Einigung’) between the parties, which was sufficient to acknowledge priority for the European patent (BGH, X ZR 49/12 — Fahrzeugscheibe, points 12 to 18).

In a decision of the High Court of Justice of England and Wales (Accord v RCT [2017] EWHC 2711 (Ch)), entitlement to priority was critical because it could not be shown that the applicant's entitlement to priority had been secured by the date of the subsequent application (point 66). Reference was made to earlier case law which ‘accepted a significant softening to what otherwise might have been the rigour of the rule that the title must be secured by the time the international application is made, by accepting an analysis based on common law principles distinguishing the equitable and legal title to property’. If such distinction could be made, it was sufficient for the applicant to hold ‘the equitable or beneficial title to the priority right’ at the date of the application (point 67).

The figure below shows in a simplified manner how an inventor (or their employer or other legal successor) may obtain international patent protection, using the priority system established under the Paris Convention.

The inventor may apply for a patent in every territory or may transfer the right to obtain a patent to separate applicants for the different territories. Inventors often assign the right to the patents in all territories to a single applicant who then files a priority application. Within the priority period, the priority applicant or other applicants may file patent applications in other territories which benefit from the application date of the priority application (i.e. the priority date).

The dashed and the dotted lines represent the right to file a patent (evolving into the title to the patent application after filing in the respective territory). Applicant B may obtain the right to file a patent for territory 2 from the priority applicant who acquired the rights for all territories from the inventor. Applicant B may also acquire the right to file a patent for territory 2 directly from the inventor. Within international groups of companies, the inventor's employer company may acquire the rights for all territories and then vest its subsidiaries in the different territories with the patent rights for the respective territories. These possibilities reflect the fact that the title to a patent application is a property right that is established and may be transferred for each territory in accordance with the laws of the respective territory.

The priority right (straight lines) may be obtained only as a consequence of the filing of the priority application (see below points 83 ff). The priority applicant needs to provide any subsequent applicant with the documents required in the respective territory for claiming priority. The priority right remains relevant for the subsequent application and any patent based thereon but it is not relevant for the priority application.

If the priority applicant (Applicant A) transfers the title to the subsequent application to the subsequent applicant (Applicant B), this transfer is normally realised together with the transfer of the priority right (encircled arrows). In the agreements discussed in priority entitlement cases, no distinction is usually made between the two transfers (see below points 93 ff). Also in the existing EPO case law under Article 87(1) EPC (see above points 58 ff), it is not always clear whether the transfer at issue encompasses only the priority right or also the title to the subsequent European application. However, the fact that different parties are potentially involved in the transfer of the different rights already shows that a clear distinction should be made between the title to the subsequent application and the priority right, i.e. the right to attribute the date of the priority application to this application. As will be shown in the following paragraphs, only the transfer of the priority right (straight line) is relevant for the proceedings before the EPO for the purposes of Article 87(1) EPC.

Low standards for a valid transfer of priority rights not only serve the purpose of harmonisation with national laws that could be applicable instead of the autonomous law of the EPC. They serve the purpose of priority rights, namely to facilitate international patent protection, by reducing the risk that the inventors' (or their legal successors') interest in obtaining patent protection in multiple jurisdictions is jeopardised by formal requirements they may inadvertently fail to meet.

Any party transferring the right to a subsequent application wishes, under normal circumstances, that the subsequent applicant may benefit from the priority right. The Enlarged Board agrees with respondent I in that it is difficult to imagine a realistic scenario in which a party would transfer their rights to the invention but intentionally withhold the relevant priority right (see p. 8 of respondent I's letter of 5 May 2023). This applies also in cases where the title to the subsequent application is not transferred from the priority applicant (see the figure in point 74). The title to the priority application and the title to the subsequent application originate from the same inventor who normally desires that the priority is valid for all subsequent applications. In this context, it must be assumed that the priority applicant who has not acquired the right to the subsequent application accepts or at least tolerates the use of the priority by the subsequent applicant.

The content of the priority application is, in general, not published or otherwise made accessible to third parties before the expiry of the twelve-month time limit for filing subsequent applications. A copy of the priority application must be filed with the EPO within sixteen months after the filing of the priority application under Rule 53(1) EPC while the publication of the priority application normally occurs eighteen months after its filing date. Moreover, the applicant of the subsequent European application must provide documentation that cannot normally be obtained without the cooperation of the priority applicant. In particular, a copy of the priority application certified as correct by the authority where the priority application was filed, must be filed with the EPO (Rule 53(1) EPC, see also Article 4D(1) Paris Convention).

These formal requirements for claiming priority in accordance with Article 88(1) EPC can only be met by the subsequent applicant if the priority applicant provides the necessary support completely and in time. The fulfilment of these requirements can thus be seen as strong factual evidence of the priority applicant's approval of the subsequent applicant's entitlement to priority.

The Enlarged Board comes to the conclusion that entitlement to priority should in principle be presumed to exist to the benefit of the subsequent applicant of the European patent application if the applicant claims priority in accordance with Article 88(1) EPC and the corresponding Implementing Regulations. This conclusion is reached taking into account (i) that 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.

The presumption also applies if the title to the subsequent application has not been acquired from the priority applicant but from a third party having the right to the invention in the respective territory (for example, from the inventor, see above the figure in point 74). Also in this situation, the priority applicant must provide the necessary support under Article 88(1) EPC, and the common predecessor with respect to the title to the two applications must be deemed to consent to the subsequent applicant's reliance on the priority right like any priority applicant assigning the title to the subsequent application.

The considerations leading to the presumption of priority entitlement apply to any case in which the subsequent applicant is not identical with the priority applicant but receives the support of the priority applicant required under Article 88(1) EPC. It does not matter whether the subsequent European application stems from a PCT application. It is also not relevant whether and to which extent the members of a plurality of co-applicants for the priority application overlap with the group of co-applicants for the subsequent application.

The presumption should be rebuttable since in rare exceptional cases the priority applicant may have legitimate reasons not to allow the subsequent applicant to rely on the priority. Such circumstances could, for example, be related to bad faith behaviour on the side of the subsequent applicant or to the outcome of other proceedings such as litigation before national courts about the title to the subsequent application.

Priority entitlement is not relevant before the priority is claimed by the subsequent applicant in accordance with Rule 52 EPC, normally at the filing date of the subsequent application or otherwise within sixteen months from the filing date of the priority application. Consequently, the presumption of entitlement exists on the date on which the priority is claimed and the rebuttal of the presumption must also relate to this date. Later developments cannot affect the rebuttable presumption.

The rebuttable presumption involves the reversal of the burden of proof, i.e. the party challenging the subsequent applicant's entitlement to priority has to prove that this entitlement is missing. If there is a strong presumption, the hurdle for rebutting it is higher than in the case of a weak presumption (see T 63/06, Reasons, point 3.2 for the rebuttal of the presumption of sufficiency of disclosure). The presumption that the subsequent applicant is entitled to the priority right is a strong presumption under normal circumstances since the other priority requirements (which establish the basis for the presumption of priority entitlement) can usually only be fulfilled with the consent and even cooperation of the priority applicant (see above points 104 ff). The party challenging the entitlement to priority can thus not just raise speculative doubts but must demonstrate that specific facts support serious doubts about the subsequent applicant's entitlement to priority.

Like the priority entitlement in general (see above points 85 f), the presumption of its existence and the rebuttal of this presumption is subject to the autonomous law of the EPC only. Consequently, there is no room for the application of national laws on legal presumptions and their rebuttal.

The PCT joint applicants approach implies that in a PCT application where parties A and B are applicants for different designated States, both applicants may rely on the priority right derived from a priority application filed by only one of the applicants, without the need for any transfer of priority rights (above point 11). Even if the ‘joint applicants approach’ is acknowledged for regular European patent applications (see above point 10, T 1933/12), the use of this approach for a PCT application with different applicants for different designated territories is questionable and has been questioned in the referring decision (see Reasons, points 30 to 33).

Under Article 118 EPC — a provision regularly quoted in support of the ‘joint applicants approach’ -, different applicants for different designated Contracting States shall be regarded as joint applicants or proprietors for the purposes of the proceedings before the EPO, and the patent shall be uniform for all designated States. Exceptions from the uniformity of the European patent are foreseen in Article 118 EPC and may be justified, for example, by prior rights based on national patent applications (Article 139(2) EPC).

The PCT does not contain a provision like Article 118 EPC, which would impose a common procedural role throughout the grant proceedings to a plurality of applicants and prescribe the uniformity of the patent for different designated territories. A PCT application, after being accorded an international filing date, has the effect of a regular national application in each designated State (Article 11(3)

PCT) which is prosecuted by the respective applicant for each designated State. The examination is carried out by the patent offices of each designated territory according to its own rules. The PCT does not exclude that different priority rights exist for different designated territories, be it for material reasons (e.g. the ‘same invention’ criterion may be interpreted differently and is dependent on the subject-matter claimed before the respective patent office), be it for formal reasons (e.g. the applicant for one territory may not be entitled to a priority right while another applicant for another territory is entitled to claim priority stemming from the same priority application).

However, a general decision on the viability of the PCT joint applicants approach is not needed. The concept of an implied agreement (below points 122 ff) should allow an assessment leading to the same result as the PCT joint applicants approach in most cases.

Where no formal requirements for the transfer of priority rights exist, priority rights can be transferred under an informal or implicit agreement (see the German case referred to above in point 72, where an implicit agreement was found to be sufficient to acknowledge priority entitlement). In the situation addressed in question II, the priority applicant (party A) actively presents itself together with the other subsequent applicant (party B) as an applicant to the office where the subsequent application is filed. Together they claim priority from the priority application of party A to the benefit of both parties. Even if the subsequent PCT application may be filed by a joint representative, the priority applicant should know about the details of this application and the related proceedings, including the claiming of priority that also benefits its co-applicant.

The Enlarged Board concurs with the referring board in that in the circumstances described in question II, the mutual filing demonstrates — absent indications to the contrary — the existence of an implicit agreement between party A and party B, conferring party B the right to benefit from the priority for the EPC territory (referring decision, Reasons, point 38).

The joint filing of the PCT application cannot in every case establish final proof of the existence of an implied agreement. However, under normal circumstances it can be assumed that the priority applicant and co-applicant for the subsequent application (party A) agrees that the subsequent application should take the full benefit of the priority for all applicants. Party A or its predecessors (including the inventor) normally have a common interest with party B in the validity of the priority for all territories encompassed by the subsequent PCT application.

The Enlarged Board concludes that, in the absence of clear indications to the contrary, the joint filing of the subsequent PCT application sufficiently proves that the parties entered into an implied agreement allowing party B to rely on the priority right established by the filing of the priority application by party A. Since the considerations leading to this conclusion not only apply in the context of PCT applications, the concept and the conditions for an implied agreement equally apply to co-applicants directly filing a subsequent European application if at least one of the co-applicants was an applicant for the priority application.

To put into question the implied agreement, evidence would be needed that an agreement on the use of the priority right has not been reached or is fundamentally flawed. For example, party B could act in bad faith to the detriment of party A who may then not be fully informed about the subsequent PCT application. A dispute between the parties at the relevant filing date was mentioned in an amicus curiae brief (efpia) as a further example (point 3.2). Factual indications putting into question the implied agreement have to be of a substantial nature and have to be presented by the party questioning the implied agreement. The implied agreement is to be assessed under the autonomous law of the EPC, which does not foresee any formal requirements for the transfer of priority rights (above point 86). Assessing the existence of an implied agreement under the autonomous law of the EPC is consistent with the approach chosen for the rebuttable presumption for the priority entitlement (above point 86) and appropriate in view of the object of the implied agreement, which is governed by the EPC and the Paris Convention only.

Transfers of private rights and underlying agreements are normally subject to national civil laws, but there are instances where the EPC regulates aspects of national civil laws in order to establish uniform standards (see e.g. Article 72 EPC on the form of the assignment of a European patent application or the development of an autonomous concept of universal succession in T 2357/12). In this context, it is justified in the Enlarged Board's view to consider the agreement implied by the joint filing of a subsequent application to be an agreement governed only by the autonomous law of the EPC.

An agreement (regardless of its form) can only be held against parties who were involved in the facts establishing the agreement. Co-applicants for the priority application who were not involved in the subsequent application may not be deemed to have consented to the reliance on the priority right by the other co-applicants for the priority application (a situation underlying e.g. T 844/18). The subsequent applicant(s) may however still be entitled to claim priority since the rebuttable presumption of entitlement does not depend on whether the involved applicants acted as co-applicants at any stage.

The subsequent applicant wishing to file a European patent application should not only hold the title to that European application (i.e. the right to the European patent) but also the priority right if such right is claimed for the European application. In the context of the EPC and the proceedings before the EPO, a strict distinction should be made between the two rights. The title to the subsequent application, on the one hand, is subject to national property laws. Its transfer is governed by national laws (to be determined in accordance with national conflict of laws rules) and assessed by national courts in view of Article 60(3) EPC (above points 79 ff). The right to claim the priority date for the subsequent European application, on the other hand, has been shown to be a right created under the autonomous law of the EPC and the Paris Convention, the transfer of which should also be assessed under the autonomous law of the EPC (above points 83 ff).

The exclusive application of the autonomous law of the EPC to the transfer of priority rights removes the need for conflict of laws 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 Article 87(1) EPC. After evaluating various arguments supporting and denying this competence of the EPO (above points 83 ff, 93 ff), the Enlarged Board concludes that the EPO is competent to assess priority entitlement.

In view of the interests of the parties involved, the lack of formal requirements for the transfer of priority rights and the necessary cooperation between the priority applicant and the subsequent applicant in the context of the procedural requirements under Article 88(1) EPC, the Enlarged Board concludes that the entitlement to priority should be presumed to exist. This presumption should be rebuttable to take into account rare exceptional cases in which the claiming of the priority by the subsequent applicant appears to be unjustified (above points 101 ff).

If the requirements under Article 88(1) EPC are not fulfilled, the subsequent applicant is barred from claiming priority for this reason alone. The fulfilment of these procedural requirements is not covered by the rebuttable presumption. This is reflected in the order where compliance with Article 88(1) EPC and the corresponding Implementing Regulations is set as a condition for the rebuttable presumption of priority entitlement. The referral is not addressing any aspect of how these procedural requirements are addressed by the EPO.

Like the nature and the effects of the priority right and the entitlement to priority, the rebuttable presumption in favour of the priority entitlement is subject to the autonomous law of the EPC. It cannot be excluded, however, that in the context of the rebuttal of the presumption national laws need to be considered as well. For example, the existence of legal entities being parties in transfers of priority rights may be relevant and may need an assessment under national laws.

Question II addresses a specific situation in which the EPO has to assess priority entitlement (given the positive answer to question I). The question concerns a group of cases where an applicant other than the priority applicant wishes to rely on the priority right for a subsequent application jointly filed by both applicants. The considerations leading to the rebuttable presumption of priority entitlement apply regardless of whether the subsequent application is a PCT application and in any case where the priority applicant (as an individual or a group) is not identical with the subsequent applicant(s) (above points 101 ff, 107). The rebuttable presumption that the subsequent applicant is entitled to rely on the priority right derived from the priority application therefore fully applies to the situation addressed in question II.

For the situation addressed in question II, it has been proposed to extend the acknowledged ‘joint applicants approach’ to a ‘PCT joint applicants approach’ which has been questioned in the referring decision and by the Enlarged Board (above points 118 ff). As an alternative reasoning for a positive answer to question II, the concept of an implied agreement has been proposed not only by the referring board but also in certain amicus curiae briefs. The Enlarged Board concurs with the referring board in that in the circumstances described in question II, the mutual filing demonstrates — absent indications to the contrary — the existence of an implicit agreement between party A and party B, conferring party B the right to benefit from the priority for the EPC territory (referring decision, Reasons, point 38).

The Enlarged Board leaves open the validity of the ‘PCT joint applicants approach’ but endorses the concept of an implied agreement. It therefore concludes that, in the absence of substantial factual indications to the contrary, the joint filing of the subsequent PCT application sufficiently proves that the parties entered into an implied or informal agreement allowing party B to rely on the priority right established by the filing of the priority application by party A.

An agreement cannot be implied if not all of a plurality of priority applicants are applicants or co-applicants for the subsequent application (the situation underlying e.g. T 844/18, above point 128). However, the rebuttable presumption of priority entitlement can be applied also in situations where one of the priority applicants is not involved in the filing of the subsequent application. In specific contexts, a priority applicant missing from the subsequent application may have reasons to claim the title to the subsequent application (in proceedings before national courts) or may possess evidence to rebut the presumption of priority entitlement in proceedings before the EPO.

The interpretation of a joint filing as sufficient proof for an implied agreement on the joint use of the priority right in the context of a joint PCT application may apply independently from the rebuttable presumption addressed in connection with referred question I. An implied agreement in the situation addressed in question II can however reinforce the presumption of entitlement to priority stipulated in view of referred question I.