Minerva Surgical, Inc. v. Hologic, Inc.

Csaba Truckai invented the NovaSure System, a device that treated uterine bleeding using a moisture-permeable applicator. After Truckai filed a patent application with the US Patent and Trademark Office (PTO), he assigned his interest in the application to his company, Novacept, Inc. The PTO issued the requested patent. Hologic, Inc. (plaintiff) later acquired Novacept and its assets, including the patent. Truckai then founded Minerva Surgical, Inc. (Minerva) (defendant), developed a device to treat uterine bleeding using a moisture-impermeable applicator, and obtained a patent. In the meantime, Hologic filed a continuation application with the PTO, seeking to add a patent claim to the NovaSure patent that covered applicator heads generally, without reference to moisture permeability. The PTO issued the amended patent. Hologic then sued Minerva, alleging that Truckai’s new device infringed Hologic’s patent. Minerva argued that Hologic’s amended patent was invalid because the added claim did not match the patent’s description of the invention, which expressly referenced moisture permeability. Hologic countered that because Truckai assigned the original patent application to Hologic’s predecessor, assignor estoppel prevented Truckai from challenging the patent’s validity. The district court agreed and found Minerva liable for infringement. The Federal Circuit affirmed regarding assignor estoppel. The United States Supreme Court granted certiorari.