Tennessee Valley Authority v. Hill

Hill and other Tennessee residents (plaintiffs) sued the Tennessee Valley Authority (TVA) (defendant) to halt a nearly finished dam and reservoir, first succeeding on environmental-review grounds. While that injunction was in place, a scientist discovered a new species of fish, the snail darter, living in the affected waters; the Secretary of the Interior listed it as endangered and found the dam would totally destroy its only known habitat, triggering Endangered Species Act protections. Plaintiffs then sued to permanently enjoin completion of the dam on that basis; the district court denied the injunction, but the court of appeals reversed and ordered a permanent injunction, and the Supreme Court granted certiorari.