What patent practitioners can learn from Nalpropion Pharmaceuticals, Inc. v. Actavis Laboratories FL, Inc.

Abstract

In its Nalpropion Pharms., Inc.v.Actavis Labs. FL, Inc. decision, the US Federal Circuit provided a narrow window for satisfying the requirement for written description of a patent claim through an ‘equivalent disclosure’.1 During the course of examination of a patent application, Nalpropion v.Actavis may allow a patent prosecutor to argue for the allowability of a claim when there would otherwise be insufficient written description in the application as filed. Similarly, counsel for a plaintiff asserting a patent in litigation may be able to draw on Nalpropion to support the validity of a claim. However, the limitations on when an ‘equivalent disclosure’ may be used to satisfy the written description requirement and the ambiguities in the Nalpropion decision highlight the importance of ensuring that sufficient explicit written description supporting the claims is included when preparing a patent application, including fully defining each claim element within the claim...