When a client has a commercially important product, it is important to build up as much patent protection as possible. This involves filing multiple patent applications and it is crucial that care is taken that each application covers different aspects of the product.

Enlarged Board of Appeal (EBoA), which is the highest authority within the EPO, in G4/19 on double patenting. Many applicants have parallel patent applications with the same priority dates, for example it is often prudent to file a “divisional” application before grant of a first European patent, and indeed there may be a chain of multiple divisional applications. This decision affirmed that double patenting is not allowed, each patent being granted must be directed to a different subject matter. Because of this, it is critically important that great care is taken when drafting claims of divisional patent applications.