“Double-patenting” arises at the European Patent Office (EPO) when one applicant files two European patent applications with closely related or identical claims, and the same effective filing date. The issue often arises when the claims of a divisional application overlap with the claims of its parent application. There is no explicit legal basis in the European Patent Convention (EPC) for the prohibition against double-patenting. However, the Guidelines for Examination at the EPO state: it is an accepted principle in most patent systems that two patents cannot be granted to the same applicant for one invention (G, IV, 5.4).

In G 1/05 and G 1/06 the Enlarged Board of Appeal decided that double patenting should be prohibited because the applicant “had no legitimate interest in proceedings that gave rise to the grant of a second patent in respect of the same subject-matter for which he already held a patent” (G 1/05, r. 13.4)”.

In the case from which the referral arises, T0318/14-3.3.01 (minutes here), the main claim request is identical to the granted claims of the European application from which priority is claimed. Thus, the applicant has a legitimate interest because the second patent claiming priority will have a later expiry than the first priority patent.

The Board of Appeal has referred the following questions to the Enlarged Board of Appeal:

1. Can a European patent application be refused under Article 97(2) EPC if it claims the same subject-matter as a European patent granted to the same applicant which does not form part of the state of the art pursuant to Article 54(2) and (3) EPC?

2.1. If the answer to the first question is yes, what are the conditions for such a refusal and are different conditions to be applied where the European patent application under examination was filed

  1. a) on the same date as, or
  2. b) as a European divisional application (Article 76(1) EPC) in respect of, or
  3. c) claiming the priority (Article 88 EPC) in respect of a European patent application on the basis of which a European patent was granted to the same applicant?

2.2. In particular, in the latter case, does an applicant have a legitimate interest in the grant of the (subsequent) European patent application in view of the fact that the filing date and not the priority date is the relevant date for calculating the term of the European patent under Article 63(1) EPC.

A previous decision, T 1423/07, relating to similar issues was considered by the Examining Division to not apply because the parties were not identical, whereas, in this case, the applicants are identical. In T 1423/07 The Board of Appeal found that legal basis for preventing double patenting cannot be found in Article 125 EPC or Article 60 EPC, and that an applicant may have a legitimate interest in the pursuing the second application in cases of internal priority. In contrast, in T307/03, The Board of Appeal found that Article 60 EPC prevents double patenting even in cases of internal priority. Internal priority is where an EP application claims priority to a previous national application filed in a designated EPC contracting state or to a previous European application.

Why is this important?

Depending on the decision from the Enlarged Board of Appeal, it might be possible to extend patent term with a filing strategy that makes use of internal priority in this context.

For further information on the EPO opposition and appeal procedures and associated strategies, including coordinating with corresponding US proceedings, please go to our webinar here on the strategic use of post grant challenges.