In the case of Minerva Surgical Inc. v. Hologic Inc., 2020, the U.S Supreme Court was asked to consider whether a patent owner should be able to assert its rights against an alleged infringer who claims that the patent is invalid because it was assigned by someone who lacked authority to do so. The dispute arose when Hologic sued Minerva for infringement on two patents related to endometrial ablation devices used in gynecological surgery, which were initially developed and patented by Csaba Truckai, co-founder of both companies. After leaving Hologic and starting Minerva, Truckai challenged his own previous patents' validity as part of defense strategy against infringement allegations made by Hologic. The central issue revolved around 'assignor estoppel', a doctrine preventing inventors from assigning their patent rights then later challenging the validity of those same patents after they have been transferred or sold. Minerva argued that this principle should not apply if there are substantial changes in law or fact since assignment occurred; while Hologic maintained it protects fairness and integrity within contractual relationships surrounding intellectual property transfers.

The dissenting opinion in the case of Minerva Surgical Inc. v. Hologic Inc., 2020, argued that the majority's decision to uphold but narrow the doctrine of assignor estoppel was incorrect and inconsistent with patent law principles. The dissent believed that this doctrine, which prevents a party who assigns a patent from later challenging its validity, should be completely abolished as it is outdated and not supported by modern legal precedents or statutory text. They pointed out that Congress has never codified this common-law principle into statute despite numerous revisions to patent laws over time. Furthermore, they noted that other countries do not recognize such a principle in their own patent systems either due to its potential for stifling innovation and competition within industries where patents play an important role.