The recent effort of environmentalists and others to secure progressive social change at the state level enacts a familiar ritual in the history of American federalism. Political actors who have found their initiatives blunted at the national level have often turned to the states. With the ebb and flow of political power between two parties over time, arguments about the relative authority of federal and state governments display far more expediency than principle, far more mutability than predictability. States may be more or less progressive than the national government, depending in good measure on the temper of the times and the relative success of political movements in particular states and regions of the country. If states do not inv...