Gary Thacker’s boat struck a partially submerged power line that Tennessee Valley Authority workers were raising from the Tennessee River, seriously injuring Thacker and killing his passenger. Thacker sued the TVA for negligence. The district court dismissed the action on sovereign-immunity grounds, and the Eleventh Circuit affirmed by applying the discretionary-function test used under the Federal Tort Claims Act. The Supreme Court reversed and remanded. It held that the TVA’s statutory promise that it may sue and be sued is not subject to an automatic discretionary-function exception. The Federal Tort Claims Act’s exception does not apply to TVA activities, and any implied restriction must be necessary to avoid grave interference with a governmental function. On remand, the court must first decide whether the challenged conduct was governmental or commercial. If it was the kind of conduct an ordinary power company performs, the TVA could not invoke sovereign immunity and would be liable like a private company. The opinion is a major clarification of the TVA’s waiver of immunity and the difference between governmental ownership and governmental conduct.