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The prohibition of double patenting for identical European patents

Date: 7 July 2021

In the recent decision of the Enlarged Board of Appeal on 22 June 2021 - G4/19, see G 4 19 EBA decision it was decided that it is not possible for two European patents to be granted with identical claims even if both patents are from the same applicant and have the same effective filing date.


The decision found that a European patent application may be refused in grant proceedings under Articles 97(2) and 125 of the European Patent Convention (EPC) if it claims the same subject-matter as a European patent granted for the same applicant (i.e. 100% identical claims) and does not constitute prior art under Articles 54(2) and (3) EPC. In arriving at this finding, the Enlarged Board of Appeal took into account the positions on double patenting expressed by the various participating nations during the Diplomatic Conference for the adoption of the EPC, the majority of which prohibited double patenting in their national laws. As such, the finding is based on assessing what the relevant aspects of the EPC were intended to mean rather than merely what they currently say. This has been done by looking to the discussions of the founding principles of the EPC during the Diplomatic Conference, and by looking at these in the light of the methods of interpretation set out in the Vienna Convention on the Law of Treaties.


It was further held that the rejection can be made irrespective of whether a European patent application was:


  1. filed on the same date;
  2. constitutes an earlier application or a divisional application (Article 76(1) EPC); or
  3. claims the same priority (Article 88 EPC), 


as an already granted European patent.


Whilst this may sound legalistic, the question of the viability of double patenting has practical consequences for Applicants and is not merely of academic interest. For instance, if a European patent application A is filed on a certain filing date and subsequently within the 12 month priority period a later European application B is filed which claims priority to application A, any patent granted from application B will have a term 1 year longer than any patent granted from A. This is because the term of a patent is calculated as 20 years from the filing date and not the priority date. Hence it would be in the interests of Applicants to use this mechanism to achieve an effective 21 year term of protection for the subject matter of the original application A. In the case of patents with high commercial value, this additional year can be a highly important, allowing an additional year of market exclusivity corresponding profits or licensing potential.


However, despite the above advantage, the Enlarged Board of Appeal did not recognise this as being a legitimate interest. Hence, in contrast to an earlier decision of a board of appeal in T 1423/07, the Enlarged Board of Appeal found no reason for deviating from the prohibition of identical double patenting.


Further comments


This decision does not affect double patenting in applications filed by different Applicants for the same subject matter on the same filing date. In other words, it is still possible that two identical patents can granted to different Applicants even in the unlikely event that the claims are absolutely identical.


Divisional applications whose claims differ from those of the first granted (parent) patent also remain unaffected (cf. an obiter dictum in earlier decisions G 1/05 and G 1/06, see EPO - G 0001/05 (divisional application/ASTROPOWER) of 28.6. 2007: "The board recognises that the principle of the prohibition of double patenting is based on the fact that the applicant has no legitimate interest in a procedure leading to the grant of a second patent for the same subject-matter for which he already holds a patent", point 13.4, first sentence in G1/05 and G1/06). It is not entirely clear to what extent problems arise if, for example, dependent claims are included in a divisional which have identical scope to claims already granted, however these should simply be deleted or adapted if objections are raised by the Office.


Also unaffected are national regulations which allow a possible prohibition of double patenting, as laid down in Art. 139(3) EPC. In Germany, a prohibition of double protection by a European and a German patent of the same family is provided for in Art. II § 8 of the Law on International Patent Conventions, see Art II § 8 IntPatÜbkG - Einzelelnorm (gesetze-im-internet.de). Similarly, for the UK double patenting between a European patent and a UK patent of the same family is prohibited by Section 73 of the UK Patents Act. 


Should this problem arise, a possible way out (not indicated in the decision) may be by filing a request for revocation of the already granted patent according to Articles 105a and 105b EPC (this has ex tunc effect, i.e. the patent is deemed never to have been granted at all).


It’s important to note that there is no prohibition against filing identical applications, merely against the grant of identical patents for the same applicant and filing date. Hence it is still possible to file identical applications, e.g. two divisional applications each with the original set of claims, but these must be amended during the prosecution procedure so that identical granted patents don’t result.


What we can do for you


There should usually be no issue on avoiding double patenting during the grant procedure, and hence we will be happy to advise on how grant procedures can be suitably coordinated.


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