The United States Congress and the governor of Florida have devoted extraordinary and all but single-minded energy to keeping Terri Schiavo alive. But all they have achieved so far is a bitter lesson in judicial supremacy. It is a lesson as old as Marbury v. Madison, the 1803 case in which Chief Justice John Marshall famously said that "it is emphatically the province and duty of the judicial department to say what the law is," and as fresh as Bush v. Gore, the 2000 decision that decided a presidential election. Its latest teachers were Judge George W. Greer, of the...