Minerva Surgical, Inc. v. Hologic, Inc. Supreme Court of the United States, 2021 141 S.Ct. 2298

The question presented in this case is whether the judge-made doctrine of assignor estoppel,which limits an inventor's ability to assign a patent to another for value and later contend in litigation that the patent is invalid, is still good law. A five-Justice majority held that the doctrine is still good law, but went on to clarify that it reaches only so far as the equitable principle long understood to lie at its core.The Court clarified that the doctrine only applies when the assignor's claim of invalidity contradicts explicit or implicit representations he made in assigning the patent. The Court provides the following examples of when the doctrine does not apply: (1) when the assignment occurs before an inventor can possibly make a warranty of validity as to specific patent claims, e.g., an employee assigns to his employer patent rights in any future inventions he develops during his employment, and the employer then decides which, if any, of those inventions to patent; (2) when a later legal development renders irrelevant the warranty given at the time of assignment, e.g., the governing law changes in a manner that renders previously valid patent claims invalid; and (3) when an inventor assigns a patent application, rather than an issued patent, and the patent claim that ultimately issues is materially broader than the claims appearing in the originally assigned application. The case was remanded for the Federal Circuit to address whether the patent owner's new claim is materially broader than the ones the inventor assigned. Justice Alito filed a dissenting opinion arguing that the writ should have been dismissed as improvidently granted. Justice Barrett (with whom Justices Thomas and Gorsuch joined) filed a dissenting opinion arguing that assignor estoppel was abrogated by the Patent Act of 1952. These Justices argue that that the Patent Act of 1952 does not incorporate the doctrine, and point out that the Court lacks authority to develop federal common law on the subject. This decision is the subject of a Holman Report in this edition of Biotechnology Law Report.