Minerva Surgical Inc. v. Hologic Inc. (Supreme Court 2021)
The Supreme Court has granted certiorari in this case involving the traditional doctrine of assignor estoppel.
Question Presented by Minerva: The question is whether a defendant in a patent infringement action who assigned the patent, or is in privity with an assignor of the patent, may have a defense of invalidity heard on the merits.
Question Presented by Hologic: The question presented is whether the longstanding common-law doctrine of assignor estoppel should be abrogated by this Court.
Petition for Writ of Certiorari – Opposition to Certiorari – Reply Brief;
Amicus by IP Professors (Lemley) – Engine Advocacy.
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The appellate panel in the case upheld the doctrine of assignor estoppel, but also found that an assignor could collaterally attack via IPR since the PTO does not enforce the doctrine. The panel – led by Judge Stoll — also called for reconsideration of the doctrine “as it applies both in district court and in the Patent Office.”
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There are several related doctrines here: Estoppel by Deed, Assignor Estoppel; Licensee Estoppel. Licensee estoppel in the patent context was ended by Lear v. Adkins, 395 U.S. 653 (1969). Prior to the Federal Circuit, some courts expanded Lear to also eliminate Assignor Estoppel. See., e.g., Coastal Dynamics Corp. v. Symbolic
Displays, Inc., 469 F.2d 79 (9th Cir. 1972) (per curiam). However, the Federal Circuit did not agree and has applied assignor estoppel over the decades to bar validity challenges by inventors and prior owners who are later sued for infringement. While licensee estoppel is contract focused, its property law parallel is estoppel by deed which bars a prior-owner from “denying the truth of the deed.” Estoppel by deed servers as the doctrinal foundation for assignor estoppel in patent law. Assignor estoppel is seemingly strengthened because the patent applicant publicly assures the USPTO of the patent’s validity by claiming patent rights.
In the end though, I believe that assignor estoppel only creates a strong presumption. I expect that no estoppel would apply in cases where the seller expressly reserves the right to later challenge the patent. Of course, most employee-inventors will not have the negotiation power or awareness to demand such a provision.
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