Minerva Surgical, Inc. v. Hologic Inc.: The Supreme Court Limits The Scope Of Assignor Estoppel

• Published date: 22 September 2021
• Subject Matter: Intellectual Property, Litigation, Mediation & Arbitration, Patent, Trials & Appeals & Compensation
• Law Firm: Shutts & Bowen
• Author: Mr Alexander Schneider

Rooted in the principle of fairness, the doctrine of assignor estoppel generally prevents an inventor, who had previously assigned their patent rights to another for value, from later contesting the validity of the assigned patent. On June 29, 2021, in Minerva Surgical, Inc. v. Hologic Inc., the Supreme Court upholds the doctrine of assignor estoppel, but finds that 'assignor estoppel only applies when the assignor's claim of invalidity contradicts explicit or implicit representations he made in assigning the patent.' Minerva Surgical, Inc. v. Hologic Inc., ' S.Ct. ' (2021), located at: https://www.supremecourt.gov/opinions/20pdf/20-440_9ol1.pdf.

The Court provides a few examples in which assignor estoppel would not apply allowing the inventor to contest the validity of a patent previously assigned by the inventor:

1. '[W]hen the assignment occurs before an inventor can possibly make a warranty of validity as to specific patent claims,' such as through an employment arrangement when '[a]n employee assigns to his employer patent rights in any future inventions he develops during his employment.'
2. '[W]hen a later legal development renders irrelevant the warranty given at the time of assignment.'
3. When there is a material change to the scope of the patent claims after the inventor assigns the patent application as 'the assignor did not warrant to the new claims' validity.'

The Court's decision narrowing of the scope of assignor estoppel is not limited to these three examples. However, many questions have been left unanswered.

Notably missing from the Court's examples is when prior art is later discovered after issuance of the patent. An inventor may assign their patent without any knowledge of the prior art that would later form the basis of their invalidity position. Although an inventor has 'a duty to disclose to the Office all information known to that individual to be material to patentability' during prosecution of the patent under 37 CFR ' 1.56, the inventor is not aware of all of the prior art in the universe at the time. Nor does the inventor necessarily make any explicit or implicit representations regarding prior art to which the inventor has no knowledge. The prior art forming the basis-or at least part of the basis-of the inventor's later...