Giorgio Agamben's work has become widely influential as a guide to explaining the extra-constitutional powers assumed by governments under the rubric of the War on Terror. His formulations, such as Homo Sacer and State of Exception, have been extended to apply to a wide variety of experiences of repression of liberties or social control, including the repression of Roma in Europe, of undocumented immigrants, and others. This essay argues, however, that Agamben's approach, while insightful and well-meaning, is potentially disastrous for the defense of the very liberties that those utilizing them seek to protect. By demonstrating that Agamben's categories were developed without reference to crucial historical experiences, including slavery and anti-slavery, genocide against indigenous peoples and enclosures of common land and resources, fail to provide either a convincing explanation for the rise of the phenomena he critiques, or a plausible strategy for confronting or reversing them. A re-reading of the history of the development of democracy through the struggles of exploited and marginalized groups, and a use of some of the basic categories of historical materialism is instead proposed as a more successful approach both for explaining, and defending against, the repressions and dangers Agamben warns about. (Contains 49 footnotes.)