Assignor Estoppel: Can’t We Just Leave It To Congress? (Answer: Not Really)

On Wednesday, April 21, the U.S. Supreme Court heard oral arguments in Minerva Surgical, Inc. v. Hologic, Inc., which concerns the doctrine of assignor estoppel. Generally speaking, assignor estoppel prohibits the assignor of a patent from later attacking the patent’s validity in court. Minerva argues that assignor estoppel is an ill-conceived relic of a bygone era that the Court should discard or at least substantially limit. Hologic argues that the doctrine is a bedrock part of the common law—a background against which Congress has been legislating for over a century—that the Court should preserve in full.