The most-recent intellectual-property decision by the Supreme Court concerned the issue of assignor estoppel. See Minerva Surgical, Inc. v. Hologic, Inc., No. 20-440 (S. Ct. June 29, 2021). Assignor estoppel is a concept in U.S. patent law that has its roots in 18th Century English patent law.

Basically, the principle behind assignor estoppel is that an entity that assigns a patent (an “assignor”) to another entity cannot later assert that the patent is invalid when the assignor is accused of patent infringement.

Assignor estoppel is an equitable principle, so it does not automatically apply in every case. However, the existing exceptions are pretty limited.

The Minerva Surgical assignor sought to eliminate the doctrine after it was accused of infringement. The assignor raised three arguments based upon the statutory language, case law and contemporary patent policy. However, the Supreme Court rejected those arguments.

The Supreme Court clarified that assignor estoppel occurs when an assignor makes explicit or implicit assertions during the assignment process that indicate that the patent is valid.

The Supreme Court also identified three exceptions to the doctrine. The first exception occurs when an employee is required to assign an invention to his or her employer. In such cases, the assignment occurs before the employee can make representations regarding the validity of the patent claims.

The second exception occurs when a legal development renders irrelevant the warranty given at the time of assignment.

The third exception occurs when the scope of the claims of the patent are changed by the assignee after the assignee acquires the patent.

The most-recent intellectual-property decision by the Supreme Court concerned the issue of assignor estoppel. See Minerva Surgical, Inc. v. Hologic, Inc., No. 20-440 (S. Ct. June 29, 2021). Assignor estoppel is a concept in U.S. patent law that has its roots in 18th Century English patent law.

Basically, the principle behind assignor estoppel is that an entity that assigns a patent (an “assignor”) to another entity cannot later assert that the patent is invalid when the assignor is accused of patent infringement.

Assignor estoppel is an equitable principle, so it does not automatically apply in every case. However, the existing exceptions are pretty limited.

The Minerva Surgical assignor sought to eliminate the doctrine after it was accused of infringement. The assignor raised three arguments based upon the statutory language, case law and contemporary patent policy. However, the Supreme Court rejected those arguments.

The Supreme Court clarified that assignor estoppel occurs when an assignor makes explicit or implicit assertions during the assignment process that indicate that the patent is valid.

The Supreme Court also identified three exceptions to the doctrine. The first exception occurs when an employee is required to assign an invention to his or her employer. In such cases, the assignment occurs before the employee can make representations regarding the validity of the patent claims.

The second exception occurs when a legal development renders irrelevant the warranty given at the time of assignment.

The third exception occurs when the scope of the claims of the patent are changed by the assignee after the assignee acquires the patent.