Patent Invalidation and Assignor Estoppel: Differing Standards, Minerva Surgical v. Hologic, Contract Considerations

Description

The doctrine of assignor estoppel precludes inventors who have assigned their patent rights from challenging the validity of the patent. The Federal Circuit had broadly and strictly applied the doctrine, finding that it not only barred attacks that were known to the inventor at the time of the assignment, but it also barred attacks based on invalidity defenses that were unknown—and unknowable—when the assignment was executed. In contrast, the PTAB has decided not to apply the doctrine in inter partes review proceedings, for example in IPR2015-00978, and the Federal Circuit upheld that decision in Arista Networks, Inc. v. Cisco Sys., 908 F.3d 792 (Fed. Cir. 2018). See also, Athena Automation Ltd. v. Husky Injection Molding Sys. Ltd., IPR2013-00290, Paper 18 (P.T.A.B. Oct. 25, 2013) (precedential).

In January 2021, the U.S. Supreme Court agreed to consider the viability of the doctrine in court challenges in Minerva Surgical v. Hologic, Inc., (U.S. Jan. 8, 2021). Oral arguments were heard in April 2021 to answer the question: “May a defendant in a patent infringement action who assigned the patent, or is in privity with an assignor of the patent, have a defense of invalidity heard on the merits?” At the district court and Federal Circuit levels, the answer was “no.” See Hologic, Inc. v. Minerva Surgical, Inc., 325 F. Supp. 3d 507 (D. Del. June 28, 2018) and Hologic, Inc. v. Minerva Surgical, Inc., 957 F.3d 1256 (Fed. Cir. 2020). The Supreme Court issued a 5-4 decision on June 29, 2021. The majority upheld the doctrine of assignor estoppel but explained that “the doctrine is not limitless. Its boundaries reflect its equitable basis: to prevent an assignor from warranting one thing and later alleging another. Assignor estoppel applies when an invalidity defense in an infringement suit conflicts with an explicit or implicit representation made in assigning patent rights.” Minerva Surgical v. Hologic, Inc., 594 U.S. ___ at 17 (2021). On remand, the Supreme Court has directed the Federal Circuit to determine whether the new claim, which issued after the assignment of the patent rights, is materially broader than the claims that were assigned.

Listen as our authoritative panel of patent attorneys examines the doctrine, how it has evolved in the courts, and why the PTAB has decided not to recognize it. The panel will also explain whether and how the Supreme Court’s Minerva decision affects the doctrine going forward. The panel will discuss considerations for contract provisions (for both assignee and assignor) and dealing with assignors and patent invalidation challenges.