Extension of a patent application

Added matter refers to the amendment by which the subject matter of a patent application, or of the granted patent, extends beyond the content of the application as filed. It is prohibited. Article 123(2) of the European Patent Convention and Article L. 612-6 of the French Intellectual Property Code lay down the principle. Added matter is also a ground for revocation of the granted patent, provided for in Article L. 613-25 of the Code and Article 138 of the Convention.

The added matter test

An amendment is allowable if the person skilled in the art can derive its subject matter directly and unambiguously from the application as filed, taking common general knowledge into account. This test, often referred to as the gold standard of the Enlarged Board of Appeal of the EPO, applies to additions, deletions and intermediate generalisations. First, adding a feature absent from the application is prohibited. Second, extracting an isolated feature from an example and introducing it into a claim is only allowed if that feature is not functionally linked to the others. Third, deleting a feature presented as essential amounts to added matter. The decisions of the Enlarged Board are available on the website of the European Patent Office.

Consequences in litigation

Added matter is one of the grounds for revocation most frequently raised before the Paris Judicial Court and before the Unified Patent Court. A patentee caught between added matter and an extension of the scope of protection after grant may find itself in an inescapable trap, because deleting the added feature would broaden the protection, which is equally prohibited. A limitation request sometimes offers a way out. The French provisions can be consulted on Légifrance.

Key points

In practice, every amendment made to the claims during prosecution must be traced and justified by a precise passage of the original application. That discipline determines the resistance of the patent in future litigation. The firm analyses these questions for claimants and defendants alike, as presented on the page patent nullity action.