RICHARD A. Epstein is one of the country’s most important libertarian theorists. The University of Chicago law professor first gained prominence in 1985 with Takings, which urged that the eminent-domain clause of the Constitution be transported from the technical periphery of constitutional law to its vital center. (The leading textbook at the time devoted only 8 of its 1,650 pages to the subject.) In the spare, concluding words of the Fifth Amendment—“nor shall private property be taken for public use without just compensation”—Epstein purported to find a comprehensive statement of the proper relation between the individual and the state. By his analysis, any diminution of the value of private property by taxes or regulation became a “taking.” A taking could be justified, without compensation, if it prevented harm to others. Or it could be justified if it were for “public use” (which Epstein understood according to the stringent criteria of “market failure”), and then only with just compensation. The implications were breathtaking: Major components of the Great Society, the New Deal, Progressive regulation, and any form of governmental redistribution would become unconstitutional. The courts and the academy were not convinced, of course, but the former have seen a modest revival of the takings clause, and the latter now treat the clause with respect. (The current leading casebook devotes nearly 50 of its 1,750 pages to takings.)