Under most jurisdictions two patents cannot be granted to the same applicant for the same invention [1]. Yet, there is no specific provision [2] in the European Patent Convention (EPC) governing double patenting.

Previous decisions (G 1/05G 1/06) of the Enlarged Board of Appeal (EBA) made reference to the general principle that an applicant has no legitimate interest in seeking a second patent for the same subject matter if the applicant already possesses one.  In T 1391/07 , it was noted that prohibition of double patenting was confined to patents and applications relating to the same invention as defined by the subject-matter of the corresponding claims and therefore confined to claims conferring “notionally the same scope of protection”.

In view of the apparent lack of a more precise test, the present case G4/19 [4] questions the legal basis under the EPC for refusing an application on the ground of double patenting.   

A risk of “double patenting” can happen in various situations. For instance, when filing a first national application, such as in the UK, followed by a regional application that includes the jurisdiction of the first application such as a European (EP) or an international application (PCT). It can also occur when filing a divisional application, or even when filing two separate European applications. 

In G4/19 another question asked to the board was whether the applicant would have a legitimate interest in seeking protection for the same subject matter if the second patent could offer an extended time of protection. This question stems from the fact that the term of protection of an EP application is calculated from the date of filing instead of the priority date. This raises the query about whether there should be an exception for applications with different filing dates but the same priority date. 

To answer these questions the EBA returned to the genesis of the EPC by analysing a collection of preparatory documents of the Convention known as the “travaux préparatoires” [5] including discussions relating to A125 EPC [6]. They concluded that: 

  • a European patent application can be refused if it claims the same subject- matter as a European patent which has been granted to the same applicant and does not form part of the state of the art; and
  • the application can be refused on that legal basis, irrespective of whether it 
      1. was filed on the same date as, or
      2. is an earlier application or a divisional application in respect of, or
      3. claims the same priority as the European patent application leading to the European patent already granted.

In conclusion, the EBA confirms the long-standing practice of the EPO and brings clarity to the question of double patenting. Unfortunately, the decision does not further expand on the interpretation of the “same subject matter“, which would have been useful for both applicants and practitioners alike.

In any case this decision is an important reminder that a patent portfolio requires careful management and demands a holistic view of the applications present in a patent family.  


[1] https://www.epo.org/law-practice/legal-texts/html/guidelines/e/g_iv_5_4.htm

[2] Article 125 EPC states: “In the absence of procedural provisions in this Convention, the European Patent Office shall take into account the principles of procedural law generally recognised in the Contracting States.” 

[3] It is noted that in those decisions the Enlarged Board did not explain in what way the prohibition on double patenting should be derived from the principle of a legitimate interest.

[4] https://www.epo.org/law-practice/case-law-appeals/communications/2021/20210622.html

[5] https://www.epo.org/law-practice/legal-texts/epc/archive/epc-1973/traveaux.html

[6] See point 78 of the decision which states: “Article 125 EPC expressly empowers and, indeed, possibly even instructs or obliges the European Patent Office to take into account generally recognised principles of procedural law, where the Convention is silent. Therefore, since the competent legislator, here the Diplomatic Conference, established that the prohibition on double patenting was a generally recognised principle as a question of fact, and in addition made it clear that this was a principle falling under Article 125 EPC as a matter of interpretation of the law, the Office was thereby not only empowered to apply this principle but effectively also duty-bound to do so.”



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