Most of the people who have been in contact with the patent system will be familiar with the concept of claiming priority from a previously filed application. Most of them will also be aware that it is the subsequent application that claims priority (and therefore an effective filing date) from the first application. However, claiming priority can be much more complicated than that. This is illustrated by one of the so-called “CRISPR” cases that over the past few years have drawn headlines in the world of IP.

The IPKat recently warmed up to the oral proceedings before EPO Board 3.3.08 on 13-17 January 2020 in appeal number T 844/18 by discussing the need for clarity on the so-called “co-applicants approach” when claiming priority at the EPO. The “co-applicants approach” is briefly explained by the following situation:

• A is applicant on the priority application.
• A and B file a subsequent application claiming priority from the priority application.
• Since A and B are co-applicants on the subsequent application, they are allowed to claim (together) the priority right belonging to A.

This is, however, not the only issue surrounding priority that could use more clarity from the Boards of Appeal of the EPO. Indeed, the issue at hand in T 844/18 is actually the opposite of the “co-applicants approach” (in a simplified version):

• A and B are applicants on the priority application.
• A filed the subsequent application claiming priority from the priority application.
• The patentee in T 844/18 (The Broad Institute et al. – “Broad”) argues that “any person” in Article 87(1) EPC should be interpreted to mean that any of A and B may claim the subsequent priority.

Decision T 788/05 and some subsequent decisions contradict Broad’s position. This is acknowledged in the preliminary opinion issued by the Board in T 844/18 (paragraph 38). However, the Board also acknowledges (paragraph 39) that allowing A to claim priority may actually leave B in a better position, since a lack of priority potentially leads to revocation (and hence nothing for B to reclaim), whereas a valid priority (and therefore, potentially, a valid patent) would let B recover his/her part in the patent. The preliminary opinion further seems to acknowledge that a strict formal approach to claiming priority could go against the spirit of the Paris Convention (on which the EPC’s priority system is based), which is supposed to make it easier to file patent applications worldwide.

Imagine the following situation:

• A and B together file a priority application covering aspects X and Y of the invention.
• A and B have a mutual (non-written) understanding that A owns X and B owns Y.
• A year later, they therefore file two different applications, both of which claim priority from the priority application: A files an application directed to X, and B files an application directed to Y.
• Under the approach of T 788/05, the priority could be considered invalid for both the subsequent applications.

Evidently, if A and B had done their homework and signed an assignment document, they would relatively easily be able to provide the necessary proof under the approach of T 788/05 that they are each other’s “successors in title” for X and Y, respectively. Another issue concerning the transfer of priority is that the transfer must be done before claiming priority (T 1201/14). Hence, A and B cannot assign retroactively. If, for whatever reason, A and B did not have time to complete the assignment before filing the subsequent application, another possible “fix” would be to file the two subsequent applications together and then assign each of the two subsequent applications according to their (non-written) understanding.

Bottom line is that under existing case law, it is a guide in “100 ways of getting priority wrong”. In that sense, claiming priority is a lot more unforgiving than other formal acts that must be completed in order to obtain a European patent. As an example, most missed deadlines under the current EPC can be cured by filing a request for further processing (Article 121 EPC) with payment of the appropriate fee. If the 12-month deadline for claiming priority is missed, only Re-establishment under Article 122 EPC is available, and it must be proven to the satisfaction of the EPO that the deadline was missed despite all due care under the circumstances (which is interpreted strictly).

Some even  argue that the “co-applicants’ approach” is too lenient on applicants and that only A and B (or their successors in title) may claim priority from a priority application filed by A and B. Hence, if A, B, and C were to claim the priority, they would argue that priority is invalid. Derk Visser (of Annotated European Patent Convention textbook fame) argues that T 1933/12, which introduced the “co-applicants approach” in case law, is poorly substantiated and that following T 788/05 would result in only A and B being able to claim the priority (since A and B are considered a legal unit for the priority right).

This is in our opinion in stark contrast to the realities facing patent applicants, as well as the purpose and spirit of the Paris Convention. T 15/01 concerned the issue of exhaustion of priority, but also contained remarks on the purpose of the priority right under the Paris Convention:

32. The right of priority is generally regarded as one of the cornerstones of the Paris Convention and was already incorporated in the original text of 1883 (cf Bodenhausen, Guide to the Application of the Paris Convention for the Protection of Industrial Property as Revised at Stockholm in 1967, 1969, Article 4, Section A(1), point (a); Ladas, Patents, Trademarks, and Related Rights, Vol. I, 1975, p. 456). Its basic purpose is to safeguard, for a limited period, the interests of a patent applicant in his endeavour to obtain international protection for his invention, thereby alleviating the negative consequences of the principle of territoriality in patent law.

34. In the course of the revisions of the Paris Convention, several amendments were made to its priority provisions in order to enhance their flexibility and thereby ameliorate the legal position of patent applicants. It was considered that overly strict solutions would hardly be in accord with the spirit of the Union treaty which is aimed at fostering and encouraging inventive genius (cf Actes de la Conférence réunie à Washington du 15 mai au 2 juin 1911, Berne 1911, p. 45). In particular, the Paris Convention in its present version (Stockholm Act) explicitly recognises the possibility of claiming multiple and partial priorities (cf Article 4F) and guarantees the right to divide patent applications while preserving the benefit of the right of priority also for the divisional application (cf Article 4G Paris Convention). The same principles are reflected in the corresponding provisions of the EPC, ie Articles 76(1), second sentence, and 88(2) and (3).
    
35. In the light of the above, the board disagrees with the view expressed in decision T 998/99 (point 3.1), according to which the international priority provisions contained in the Paris Convention have to be regarded as a body of exceptional rules which should be interpreted strictly. Rather, they have to be construed in a manner which ensures that the general purpose they serve, namely to assist the applicant in obtaining international protection for his invention, is fulfilled as far as possible.

This decision was cited by Broad in T 844/18 and acknowledged in paragraph 39 of the preliminary opinion of the Board. It seems difficult to reconcile with the more formalistic approach in T 788/05, and it will be interesting to see which balance is struck by the Board in T 844/18. After January 17, more clarity is hopefully achieved, but there is no guarantee. In the meantime, it is important for applicants to be aware of and comply with the formalistic approach as much as possible.

A further issue raised by Broad, but not addressed explicitly in the preliminary opinion by the Board in T 844/18 is whether the EPO is competent at all to assess the entitlement to priority. When a European patent application is filed, the EPO does not require proof of entitlement to priority from the applicant under Article 88 and Rule 52 EPC, not even if the European application is filed in a different name than the priority application. Indeed, the legislator explicitly rejected this possibility when the EPC was prepared.

Therefore, from a strict fairness perspective (which is not a legal standard per se), it begs the question why the EPO should assess priority 10-15 years later when a third party with no real interest in the priority right (other than to see the patent revoked) could oblige the EPO to make that same assessment that it was not allowed to make at the point in time (i.e. upon filing) when the applicant most easily would be able to provide the necessary proof.

It is unclear whether the Board will actually address this fundamental issue, which was not dealt with directly by a board before. Since, in the existing case law, nobody asked whether the EPO (of which the boards are a part – Article 15(f) EPC) was in fact competent, the boards dealt with issues for which they may not be competent. A parallel is Article 60 EPC, which concerns the right to the European patent application. The EPO is very explicitly not competent to deal with the issue of right to the European patent application, which issue is a matter left for national courts under the Protocol on Recognition.

Further appeal cases that may clarify the EPO’s position on the right to claim priority are T 2749/18, T 1837/19, and T 477/19 (Aera is representing the patentee in the latter appeal). A decision in any of these cases is unlikely to be available for at least another couple of years.