The right of priority, its successor in titles: more to follow …

12.12.2023Articles and Publications


Articles and Publications 12.12.23

The right of priority, its successor in titles: more to follow …

Since our comments last year in The right of priority, its successor in title: an example of international common sense to follow … – DTMV the Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) has just, on 10 October, ruled (G 01 and 02 / 22) that this priority can be the subject of an implicit agreement between the first US applicants and the second PCT applicants to benefit from it on the territory of the EPO.

While this EBA cites only its decision of 16 February 1962 in Valence, which it presents [p. 34 § 95] in a manner divergent from that adopted in particular by Professors Bodenhausen, Le Tarnec and Mathély, French case law has regularly accepted, for more than ten years, that this right of priority may indeed be the subject of an implicit assignment in favour of a third person, whom Articles 4 A 1) of the Paris Convention (PC) and 87 (1) b) of the European Patent Convention (EPC) qualify precisely as “his successor in title”.

However, French judges have stipulated that while such an assignment may be implicit or tacit, it must still be certain under its governing law.

Like any agreement between two persons, an assignment can only be governed by a single applicable law. This is clearly the case for the sale of patents (trademarks, designs, etc.) registered even in several countries, but where the substance or content of the contract is governed exclusively by the law chosen by the contracting parties.

I. The EPO’s EBA considers itself firstly competent to assess a challenge raised by an opponent as to the date on which the state of the art that he wishes to oppose to the contested patent ends, which seems quite natural.

It is generally accepted, particularly in our European procedures, that the judge of the action (demands) is also the judge of the objection raised in defence. Articles 49 of our French Code of Civil Procedure (CPC) and 32-1.a) of the Unified Patent Court (UPC) make provision for this.

In this case, although a dispute over the right of priority is not a ground for opposition, it is nevertheless common sense that in order to examine the novelty or inventive step, the EPO must, in order to decide whether or not to grant a patent, determine the state of the art to be retained, and consequently define the dates, including the priority date claimed before it.

That being said, the EBA prefers to characterise this challenge as whether this second PCT applicant is entitled to claim the priority provided for in Article 87(1) of the EPC before the EPO.

However, it is surprising that, on the grounds of the autonomy of the EPC, the EBA refuses, if not to apply, at least to examine the law of the contract which transfers the right of priority to the successor in title.

Just as the EBA admits this for national judges who each have their own conflict of laws rule, the autonomy of this 1973 “Convention on the Grant of European Patents” nevertheless allows it, if not to create its own conflict of laws rule, at least to decide that if this EPC grants the applicant before the EPO a presumption of his right to claim priority by virtue of article 88(1) of the EPC, an opponent nevertheless has the right to rebut it, in particular by challenging a so-called transfer to a successor in title, as being non-existent or contrary to the agreed contractual law.

Perhaps the EBA would have preferred to take account of the generally accepted principles in this area in the EPC countries, to which Article 125 allows it to refer.

It is true that European case law (in particular German, English, French, Dutch, etc.) differs on the grounds for assessing the transfer of priority to a successor in title:

  • is it a question of assessing the right of priority specific to this intellectual property (IP) which arises in one country only to be exercised in reality in another country, in order to erase in particular twelve months of the state of the art there?
  • or is it an assignment contract subject to the general or common obligations and rights of our laws or civil codes?

Is this not why the EBA declares [p. 42 § 115] that its solution on this rebuttable presumption in favour of the applicant before the EPO is not binding on the judges who are bound by their own conflict of laws rules?

However practical it may be, and in line with Articles 60(3) of the EPC and L. 611-6 of the French Intellectual Property Code (CPI) in favour of the applicant to exercise or have the right to a patent, will the EBA’s solution have any significant authority, particularly before our judges in Europe, for example, as well as before other Offices around the world?

Wouldn’t the EBA have had more influence even outside Europe if, applying the law agreed for the whole world between its owner and his successor in title, it had given its opinion on the transfer of this priority that arose at the time of the first filing, here in the US?


II. In these circumstances, the EBA decided as a matter of principle to grant this rebuttable presumption to the second PCT and EPC applicants [here party B], even if they are not the same as the first US applicants [here party A].

The reasoning behind this decision deserves attention. A priori, since the applicants are not the same, a link between the two parties A and B should at least be explained.

The EBA explains that “joint filing implies an agreement between parties A and B allowing party B to claim priority, ...”.

For this purpose, it appears that in reality the EBA thought it could interpret the factual situation and modify the question referred to it.

In its decision [p. 52 II § 2], the EBA considers that in the PCT application “filed jointly by parties A and B”, A is designated “for one or more designated States” and B is designated “for one or more other designated States“.

  • The EBA’s hypothesis is ambiguous, to say the least, for two reasons.
    • Indeed, the EBA itself quotes [p. 1 § 1] the question referred to it, pointing out that “the PCT application designates party A as the applicant for the US only and party B as the applicant for the other designated States, including the regional protection of the European patent” [p. 1 § 1. II. 1)].This wording of the question seems more appropriate.
    • The EBA also states [p. 1 § 2]:
      • the first application, which gives rise to the right of priority, was filed in the US in 2004 by the three inventors (natural persons)
        (Mr. Rother, Mr. Wang, and Mr. Zhong) [i.e. by party A],
      • while the PCT EPC application was filed in 2005:
        • by two US-based legal entities (the University of Ontario and Alexion Inc.) [i.e. party B] “for all designated states except the US“,
        • as well as party A designated for the US only“.


  • The question immediately arises as to what is “common“, “joint” or “jointly” about the filing of this PCT EPC application, since the rights in question are distinct and exercised independently, as well as in different territories.The three inventors filing in the US [party A] in fact wish to exercise their right of domestic priority within the US exclusively, which the PC never provided for, since the priority established there is exclusively from one country to another [article 4 A 1)]. For this reason, it should be noted that they likely had to attach the text of their US priority to their PCT application.

    Party B [the two PCT EPC applicants], on the other hand, wishes to exercise exclusively the right of international priority provided for in the PC, outside the US to the rest of the world and in particular to Europe.

In these circumstances, it is by no means certain that in Europe or on other continents, national judges will follow the EBA’s assumption to admit a presumption in favour of those second PCT EPC applicants who claim the international priority of the PC, even if this claim is deemed to comply with Article 88 (1) EPC.

What’s more, the evidence to the contrary that would destroy this presumption seems obvious.

Because a priori :

  • the first US inventor applicants [party A] only exercised a domestic US right in their PCT application, which is not the right provided for abroad by the PC, even though this application was presented in a single form signed by a common representative,
  • whereas, in the opposite direction, the second PCT EPC applicants [party B] had given this representative the task of enabling them to benefit outside the US from the international priority provided by the PC, in particular in Europe via the EPC.

It remains to be seen whether:

  • in particular in view of the assignment of his right of priority by one of the three inventor applicants in the US, but the non-existence of any such assignment by the other two prior to the filing date of the PCT EPC application (in other words during the life of this right of priority) [p. 2 § 4],
  • the law of the original contract (in this case, it would be a US law) [see p. 22 § 64 and 65, p. 37 § 100] makes it possible, even after the priority right has expired, to confirm expressly that, before it expired, each of parties A and B had indeed intended to assign and acquire with certainty not only the right to file patents abroad, but also the right of international priority of the PC, which the EBA distinguishes from the other attributes of the patent right arising from its first filing.

Finally, while the EBA points out that the PC, PCT and EPC are intended, under certain conditions, to provide the best possible protection for inventions in several countries, and that the EU Charter guarantees IP among its fundamental rights, European judges, who are also bound by their full jurisdiction to assess (especially after a patent has been granted) a patent infringement, are keen to respect the principle of proportionality between these fundamental rights, which are IP and freedom to exploit what must remain available to all.

To be continued …

Thierry Mollet-Viéville

                                                                         avocat à la Cour – DTMV

                                                                         former president of Aippi and of Afppi


                                                                         December 8. 2023