Double patenting

Double patenting refers to the situation in which the same invention is covered by two titles belonging to the same proprietor, whether as a result of two European applications, the coexistence of a European patent and a national patent, or the overlap of a European patent and a unitary patent. The prohibition on double patenting aims to prevent a proprietor from artificially multiplying its titles on the same invention or extending their term. Its regime differs depending on whether the question arises at European or national level.

The prohibition before the EPO

The European Patent Convention (EPC) does not expressly lay down the prohibition. The Enlarged Board of Appeal has, however, confirmed that a European patent application may be refused where it claims the same invention as a European patent already granted to the same applicant, basing that prohibition on Article 125 EPC. The rule applies whether the two applications were filed on the same day, are a parent application and a divisional application, or claim the same priority. It requires identity of the claimed subject matter, mere overlap being insufficient according to Office practice.

Coexistence of the European patent and the French patent

Article 139(3) EPC leaves it to each State to decide whether an invention protected by both a European patent and a national patent having the same filing or priority date may enjoy cumulative protection. French law used to provide for the European patent to replace the French patent covering the same invention, the latter ceasing to have effect. Reformed with the unified patent court system in view, French law now allows the two titles to coexist since the entry into force of the Agreement on a Unified Patent Court. The proprietor may thus keep a French patent subject to the national courts alongside a European patent falling within the jurisdiction of the Unified Patent Court (UPC).

The unitary patent and national validations

Regulation (EU) No 1257/2012 requires participating Member States to ensure that, where the unitary effect of a European patent has been registered, that patent is deemed not to have taken effect as a national patent on their territory. Combining a unitary patent and a national validation of the same European patent in a participating State is therefore excluded. Combining a unitary patent with a separate national patent, by contrast, depends on the law of each participating State.

Key points

Double patenting is prohibited before the EPO for claims to the same subject matter belonging to the same applicant, but French law now allows a French patent and a European patent to coexist. That coexistence opens choices of forum and strategy, particularly with regard to the UPC. When filing divisional applications, the claimed subject matter should be genuinely differentiated, and a decision should be taken on whether it is worth maintaining a French patent alongside the European or unitary patent.

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This glossary entry is general in scope and does not constitute legal advice.

Dhenne Avocats litigates patent disputes before the Paris Judicial Court, the Paris Court of Appeal and the Unified Patent Court. Where the question arises in a real case, the useful moment is almost always before proceedings are issued.

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