With the discovery of a tiny fish in a soon-to-be-flooded stretch of the Little Tennessee River, construction on a dam that had already cost taxpayers $100 million came crashing to a halt. Thanks to the Endangered Species Act of 1973, the snail darter was instantly transformed into both an icon for species preservation and a despised symbol of the environmental movement"s alleged excesses. The intense legal battle that ensued over its fate was contested all the way to the Supreme Court. The 1978 decision in TVA v. Hill, the Court"s first decision interpreting the Endangered Species Act, remains one of the most instructive cases in American environmental law. Affirming an injunction that prohibited the Tennessee Valley Authority from completing the Tellico Dam because it would eliminate the snail darter"s only known habitat, the Supreme Court resolved an intragovernmental dispute between the TVA and the Interior Department as well as the claims of the local opponents of the...