In its most recent decision G 4/19, the Enlarged Board of Appeal of the European Patent Office deals with the so-called prohibition of double patenting. The Board confirms therein that a European patent application may be refused if it claims the same subject-matter as a European patent, granted to the same applicant, which is not part of the state of the art. This applies irrespective of whether the application to be refused was filed on the same day as the European patent already granted, is a parent or divisional application thereof or claims the same priority as the European patent already granted.
The prohibition of double patenting is based on the assumption that the applicant has no legitimate interest in granting of a second patent for the same subject-matter for which he already owns a patent.
The European Patent Convention (EPC) does not contain any explicit provisions on the prohibition of double patenting. However, such a prohibition was derived from general principles of law (“Ne bis in idem”), for example in an “obiter dictum” in decisions G 1/05 and G 1/06. Under Art. 125 EPC, principles of procedural law generally recognized in the contracting states may be used in EPO decision-making practice, provided that corresponding provisions are not provided by the EPC.
The problem of a possible double patenting may arise for the following three situations:
- (1) Two applications containing at least one identical claim are filed on the same date.
- (2) At least one claim of a parent application and a divisional application derived therefrom are identical.
- (3) At least one claim of a first application and a subsequent application claiming the priority of the first application are identical.
A practical interest of the applicant in double patent protection exists in particular in the third of the mentioned situations. The term of a patent is 20 years. The relevant date for calculating the term is the filing date of the application, but not its priority date. This means that the maximum term of protection of a subsequent application filed one year after a first application and claiming its priority ends 21 years after the filing date of the first application. In other words, an effective extension of the term of protection by one year can be achieved for the subject-matter claimed in the subsequent application.
The question brought before the Enlarged Board of Appeal was whether a European patent application can actually be refused with reference to double patenting and, if so, whether a distinction must then be made between the above three possible situations. In particular, the question was raised whether in the practically very relevant third case (application and its priority application) a legitimate interest of the applicant in double patenting would result from the fact that the filing date and not the priority date is decisive for calculating the term of the patent.
The Enlarged Board of Appeal initially affirms that a European patent application can be refused with reference to double patenting. A prohibition of double patenting could indeed be derived from the legislative history of the EPC and can be applied under Art. 125 EPC.
Nor was it necessary to distinguish between the three situations outlined above. From the “travaux préparatoires”, i.e. the official records of the history of the proceedings of the EPC, it would be clear that the legislator did not want to distinguish between these cases. Therefore, the question of a legitimate interest of the applicant in double patenting could also remain unanswered in the case of an application and its priority application.
The decision follows the established practice of the EPO on the prohibition of double patenting, in particular the decisions G 1/05 and G 1/06. It makes explicitly clear that the prohibition of double patenting can indeed be applied under the EPC and also applies to an application and its priority application. The fact that the Enlarged Board of Appeal leaves the question of a legitimate interest of the applicant in a second patent in such a case unanswered is to a certain extent unsatisfactory. Such an interest would probably not have been easily to deny in the light of the effective extension of the term of the patent.
The decision also leaves open when two claims relate to “the same subject-matter” and therefore fall under the prohibition of double patenting. According to established practice, an application is refused with reference to the prohibition of double patenting only if the scope of protection of the claims is identical. Overlapping scopes of protection of non-identical claims, on the other hand, are generally regarded as uncritical.
Even if this question remains unanswered in the decision, it can probably be assumed, in accordance with established practice, that the prohibition of double patenting is still to be interpreted narrowly and thus remains limited to identical claims. This is also supported by the fact that the reasoning of the decision distinguishes between “double protection” (overlapping claims) and “double patenting”.