In a long awaited decision, the Enlarged Board of Appeal ("EBA") of the European patent Office ("EPO") confirmed that a European patent application can be refused on the basis of double patenting under Articles 97(2) and 125 EPC, if a patent with the same effective date has already been granted for the same subject matter. The decision revises the position previously taken by the Boards of Appeal that it is the application date—and not the effective date—that is relevant for the purpose of double patenting assessment.

Absent any direct legal provision in the European Patent Convention ("EPC"), it has been an established practice at the EPO to raise a double patenting objection in applications sharing the application date with patents granted to the applicant for identical subject matter. This situation would commonly arise in divisional applications. However, a patent granted from a priority application would not trigger double patenting because a longer protection afforded by the follow-up patent would justify an applicant's legitimate interest in having two patents. See our March 2019 Alert, "Extension of Protection for Up to One Year Possible?"

In the referral case T 318/14, the Board of Appeal asked the EBA to clarify the legal basis in the EPC for refusing an application on the ground of double patenting. The EBA was also asked whether the double patenting prohibition equally applies to all three cases, namely, (i) two separate applications having the same application date; (ii) parent and divisional applications; and (iii) a second application claiming priority from a first application—so-called "internal priority."

In its decision G 4/19, the EBA goes to great length to analyze the original legislative intent in view of the preparatory documents of the EPC as well as the national provisions. The EBA concludes that Article 125 EPC obliges the EPO to abide by generally recognized principle of procedural law such as the prohibition of double patenting. According to the EBA, it was the legislator's intent to apply this principle to all three cases mentioned above, regardless of whether there is a legitimate interest in a second patent. Thus, contrary to previous case law, an applicant will no longer be able to pursue a follow-up application, if the priority application has already matured into a patent directed to the same subject matter.

However, the EBA construed the double patenting prohibition narrowly. In particular, the EBA confirmed that the double patenting objection should only be raised when the application and the patent claim identical subject matter, have the same applicant and designate the same states. Moreover, this objection could only be raised during examination, but is not a ground of opposition. In practice, this means that a double patenting objection may be overcome, for example, by arguing that the subject matters are not identical or by introducing into the follow-up claims additional features to establish a (minor) difference to the granted patent. The applicant may also consider to "self-revoke" the earlier patent by requesting revocation before the EPO. Procedurally, this decision "unfreezes" the proceedings ,which had been stayed during the pendency of the referral.