The use of biological weapons in the United States would trigger a public health and political emergency. Governmental response to national emergencies in many countries have historically brought the rule of law under intense pressure, sometimes resulting in the abandonment of basic legal protections for populations. The use of biological weapons in the United States would threaten the rule of law because the American legal system is not designed to deal with complex acts of violence. The two areas of the American legal system most affected by a biological weapon attack would be public health law and the law managing disasters. In order to analyze the threat of bioterrorism to the rule of law, this article looks at structural, substantive, and implementation challenges bioterrorism poses for legal systems in the United States. The structural challenge involves how federalism affects efforts to prepare for and respond to a bioterrorist attack. Beneath the structural challenge, concerns arise about whether the substance of relevant areas of law can support effective responses, and whether State and Federal governments can effectively implement the actions needed to respond to a bioterrorist attack. The substantive and implementation challenges are interdependent because the failure to deal effectively with one undermines the ability to deal with the other. These three legal challenges--structural, substantive, and implementation—point to the need for a legal strategy to deal with the possible problems that a bioterrorist incident would produce. Fortunately, governmental agencies such as the Centers for Disease Control and Prevention (CDC) and non-governmental organizations are raising awareness concerning the need to include an analysis of law in the evaluation of American bioterrorism preparedness.