Old-fashioned empire is suddenly everywhere. In the United States, discussions of empire used to look as much to what we now call soft power as to the seemingly atavistic technologies of high nineteenth-century imperial powers. McDonald\u27s and Coca-Cola, Microsoft and Intel—these were the purveyors of the distinctively American empire of commerce and markets. Since 9/11, however, the traditional approach to empire has come to the fore with all the trappings: soldiers, invasions, occupations, and prisoners. Hard power is back, and so too are a set of difficult constitutional questions: about the Constitution and foreign affairs, about the significance of international law, and about the relationship of foreign affairs authority to domest...