Minerva Surgical, Inc. v. Hologic, Inc.
594 U.S. 559
| SCOTUS | 2021Background
- Csaba Truckai invented the NovaSure uterine-ablation device, filed a patent application, and assigned that application (and continuations) to Novacept, which later transferred the rights to Hologic.
- Truckai later founded Minerva and developed a different endometrial ablation device (moisture-impermeable); Minerva obtained a patent and FDA approval for it.
- Hologic filed a continuation application and obtained an amended patent claim that broadly covered applicator heads without reference to moisture permeability; Hologic sued Minerva for infringement.
- Minerva defended on invalidity grounds, arguing the broadened claim was not supported by the original written description (specification) assigned by Truckai.
- The District Court and Federal Circuit barred Minerva’s invalidity defense under assignor estoppel; the Supreme Court granted certiorari to review the doctrine’s viability and scope.
Issues
| Issue | Plaintiff's Argument (Minerva) | Defendant's Argument (Hologic) | Held |
|---|---|---|---|
| Whether assignor estoppel remains a valid doctrine | Abolish doctrine as inconsistent with §282(b) and modern patent policy | Preserve doctrine as equitable protection for assignees against inconsistency | Court upheld assignor estoppel as valid but limited by equitable principles |
| Whether the Patent Act of 1952 abrogated assignor estoppel | §282(b) makes invalidity a defense in any action, so estoppel is displaced | 1952 Act did not override background common-law doctrines including assignor estoppel | Rejected Minerva’s statutory-abrogation claim; 1952 Act did not abrogate estoppel |
| Effect of post-Westinghouse cases (Scott Paper, Lear) on the doctrine | Scott Paper and Lear effectively eliminated assignor estoppel | Those cases only narrowed—did not abolish—the doctrine | Court held Scott Paper and Lear limited estoppel but did not eviscerate it |
| Whether assignor estoppel bars challenge to claims added/broadened after assignment | Estoppel should not apply where assignee materially broadened claims beyond what assignor warranted | Assignor’s implicit representation covers assigned subject matter and bars challenge | Estoppel applies only if inventor’s later invalidity position contradicts explicit/implicit representations made at assignment; remanded to determine if Hologic’s claim is materially broader (if so, estoppel does not apply) |
Key Cases Cited
- Westinghouse Elec. & Mfg. Co. v. Formica Insulation Co., 266 U.S. 342 (1924) (recognized and grounded assignor estoppel in fair-dealing principles)
- Scott Paper Co. v. Marcalus Mfg. Co., 326 U.S. 249 (1945) (declined to apply assignor estoppel in extreme circumstance; limited doctrine)
- Lear, Inc. v. Adkins, 395 U.S. 653 (1969) (abolished licensee estoppel; distinguished assignor estoppel and urged attention to equities)
- Diamond Scientific Co. v. Ambico, Inc., 848 F.2d 1220 (Fed. Cir. 1988) (Federal Circuit revived and applied assignor estoppel principles)
- Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002) (reiterated that claims must be supported by the patent specification)