U.S. Supreme Court Upholds and Limits the Doctrine of Assignor Estoppel

August 31, 2021

A Supreme Court majority recently upheld the doctrine of assignor estoppel and limited its application. Minerva Surgical, Inc. v. Hologic, Inc., 141 S. Ct. 2298 (June 29, 2021).  Specifically, the majority held that assignor estoppel applies only when an assignor’s claim of invalidity contradicts explicit or implicit representations the assignor made in assigning the patent-at issue. Id. at 2302, 2309-10.  Concluding that the Federal Circuit’s application of the doctrine has been too expansive, the majority went on to clarify the doctrine’s scope and provide guidance for its application. Id. at 2307-2311.