Federal Circuit Reaffirms Vitality of the Assignor Estoppel Doctrine-Further Emphasizing the Importance of the PTAB

摘要

Assignor estoppel provides patent owners a powerful tool against accused infringers who attempt to assert a defense of patent invalidity. Specifically, the doctrine prevents an assignor of a patent or patent application, or an entity in privity with such an assignor, from later challenging the validity of that patent. The U.S. Court of Appeals for the Federal Circuit's recent decision in Mag Aerospace Industries Inc. v. B/E Aerospace, Inc. has reaffirmed the continued vitality of this doctrine and highlighted an often-overlooked aspect.