Supreme Court Limits Assignor Estoppel to its Equitable Core Consistent with Kramer Levin’s Amicus Brief for NYIPLA

On June 29, 2021, the Supreme Court, in Minerva Surgical, Inc. v. Hologic, Inc. et al., upheld the doctrine of assignor estoppel, vacated the judgment of the Federal Circuit, and remanded for further proceedings consistent with its opinion. On February 25, Kramer Levin had filed a merits stage amicus brief on behalf of the New York Intellectual Property Law Association, urging the Court to overturn the Federal Circuit’s per se application of estoppel in favor of an equitable approach that considers the specific facts of the case in determining whether estoppel should apply. Consistent with NYIPLA’s arguments, the Supreme Court, while endorsing the doctrine of assignor estoppel, recognized “the Federal Circuit has applied the doctrine too expansively,” and that “the doctrine is not limitless.” It clarified that its boundaries “reflect an equitable basis: to prevent an assignor from warranting one thing and later alleging another,” and assignor estoppel only “applies when an invalidity defense in an infringement suit conflicts with an explicit or implicit representation made in assigning patent rights.” Read the Supreme Court’s opinion.