Valid claiming of priority rights in patent applications

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On 16 January 2020, the European Patent Office (EPO) Board of Appeal revoked a patent related to CRISPR/Cas9 technology (See), and in doing so delivered one of the most anticipated decisions (See) in the field of biotechnology patents in recent times. This gene-editing technology, which is the subject of a bitter battle for intellectual property rights between two rival parties – The Broad Institute and the University of California (UC), Berkeley, is revolutionizing research in biotechnology.

The case concerned one of Broad Institute’s CRISPR patents, EP2771468, which was revoked owing to a jurisdictional difference in the interpretation of valid claiming of priority rights. The Broad Institute’s licensing strategy is likely to be compromised by this outcome, as UC Berkeley has already obtained a patent in Europe.

This article discusses the jurisdictional differences in the interpretation of priority rights and provides a summary of the case. 


Priority rights, as defined by Article 4A of the Paris Convention (See) is a right that “Any person who has duly filed an application for a patent…….., or his successor in title, shall enjoy, for the purpose of filing in the other countries, a right of priority during the periods hereinafter fixed”. Article 4B further states that the right cannot be invalidated during the time period specified (usually 12 months) by acts such as another filing, the publication or exploitation of the invention.  The decision upheld the EPO’s long-standing practice of requiring every applicant named on the priority application, or their successor-in-title, to also be named on the priority-claiming application. It also provides a cautionary reminder for considering jurisdiction-specific requirements when applying for a patent. 

The EPO is among many jurisdictions which distinguishes between the right to claim priority and the priority rights in an application i.e. the ownership of priority rights. The finding in this case was that the right to claim priority is a formal requirement at the EPO, which is necessary to identify the application and to determine the state of the art (i.e., assess the novelty and inventive step).

For this purpose, the EPO requires that the applicant who filed the priority application should be the same or their successors-in-title in the later-filed application. A ‘successor-in-title’ can be proven by submitting a legal document indicating the transfer of rights e.g., an assignment. By corollary, the EPO also recognizes that a priority right is indivisible and thus, for joint applicants, all applicants must be named in the subsequent applications, for the application to validly claim priority.

At the United States Patent and Trademark Office (USPTO), however, the emphasis is less on the applicants named, and more on the invention disclosed. The requirement is that the disclosed invention must be the same in both the prior applications and subsequent applications. Instead of requiring that all applicants be named in subsequent applications, the USPTO requires that ‘each prior-filed provisional application must have the same inventor or at least one joint inventor in common with the later-filed application’ (MPEP 211.01(a)) (See).

India, meanwhile, has borrowed liberally from UK patent law and therefore, priority rights and their transfer function in a manner similar to the EPO. This issue has not been tested in India as yet, and there is no relevant case law, but references during the drafting of Indian patent law, from the Ayyangar Committee Report (the Report) (See), clarify that the right to claim priority and the priority rights in an application i.e. the ownership of priority rights, should be treated separately.

For instance, the Report specifies in Clause 8, Sub-Clause (2, pt. 361) regarding Provisional and Complete Specifications  “The corresponding provision in the U.K. Act, 1949 is section 3 (3) which, however, does not specifically mention that the two or more applications accompanied by provisional specifications referred to in the clause should be in the name of the same applicant in order to attract the provisions of that section though this is implicit from the other provisions of the U.K. Act with reference to anticipation etc. The language of the sub-clause which specifically provides for the applications being in the name of the same applicant puts the matter beyond doubt and might therefore be retained”.

This paragraph from the Report clarifies that ‘the all applicants’ approach of the EPO, in view of priority applications, is also a requirement in India, as this serves to determine the state-of-the-art for the application. Further, Section 20 of the Indian Patents Act 1970, clarifies that an assignment is required in case in any change in the applicant of a patent.

For applications made to the Indian Patent Office, therefore, it is advisable to retain the names of all the applicants in a priority application in the later application, or in the case of joint applicants, to provide an assignment or an agreement by the applicants specifying their consent in the succession of title.


Patent No. EP2771468, titled ‘Engineering of Systems, Methods and Optimized Guide Compositions for Sequence Manipulation’, was granted to three co-proprietors, The Broad Institute, the Massachusetts Institute of Technology, and the President and Fellows of Harvard College. The patent claims priority to 12 US provisional applications.

The application, however, failed to mention the name of one person who was named in two priority applications; no document demonstrating the transfer of rights or succession of title was produced either.

The opponents of the granted patent cited this as a ground for revocation, and going forth, the patent was revoked under Article 87(1) of the European Patent Convention (EPC) which states that “Any person who has duly filed … an application for a patent… or his successor in title, shall enjoy, for the purpose of filing a European patent application in respect of the same invention, a right of priority during a period of twelve months from the date of filing of the first application” (See).


The case regarding EP2771468 centred around three issues: (See)

(i) EPO’s authority to assess priority rights

(ii) The definition of ‘any person’ in Article 87(1), EPC, and

(iii) Whether the interpretation of ‘any person’ should be governed by national law


The proprietors of the patent argued that the EPO was not competent to assess the priority rights to an application as the ownership of rights or entitlement falls under the jurisdiction of national courts. However, the Board held that the assessment of priority right is a procedural requirement to determine the effective date of filing for patentability purposes i.e. to determine the novelty and the inventive step. It held that the validity of the priority claim must be assessed, otherwise anyone would then be able to claim priority from the first application, which would compromise the determination of the state of the art. Therefore, the Board held that the EPO was the correct authority to assess the validity of a priority claim and dismissed the proprietors’ first argument.

The second argument related to the interpretation of the term ‘any person’ in Article 87 of the EPC and Article 4A(1) of the Paris Convention. The patentees argued for a more permissive definition of the term, in line with practice at the USPTO, which requires merely one inventor to be in common between the priority application and the subsequent application.  Established practice at the EPO, on the other hand, requires that a subsequent application should mention all the applicants named in the priority application. The Board reconfirmed this, affirming that a priority right is a single indivisible right and the applicant of the subsequent filing must be either the applicant/s of the priority filing or their successor in title.

The last issue under consideration was whether the phrase “any person who has duly filed” under Article 87(1) should be interpreted by reference to the national law of the first filing (US national law in the current case). The Board agreed with the Opposition Division’s interpretation, in that both under the Paris Convention and the EPC, the right to claim priority derives from the formal requirement of filing the first application. Thus under Articles 4A(1), A(2), and A(3) of the Paris Convention, the consideration of the term ‘any person who has duly filed’ is only to accord a date of filing and not to assess the contribution of an inventor. It, therefore, rejected that national law held precedence here.


This decision reconfirms the standard practise at the EPO of including all the applicants of a provisional application into the subsequently-filed application to validly claim priority rights. The detailed written decision of the Board of the Appeal is awaited and is likely to shed further light into the reasoning behind this approach.

As a general rule, it is therefore recommended to provide a proof of right, or an assignment indicating the transfer of rights in case of a change in the applicant(s), and in case of joint applicants, the proof of right should indicate that each of the applicants has agreed to the change. Such a practice would prevent any future issues arising due to jurisdiction specific requirements related to valid claiming of priority rights.