During the past 8 years, the US Congress has developed a comprehensive legal framework to prevent the illegitimate use of toxins and infectious agents. As part of this framework, Congress has defined as a federal crime virtually every step in the process of developing or acquiring a biological agent for use as a weapon. At the same time, Congress has vested federal law enforcement agencies with broad civil and investigative powers to enable the government to intervene before such weapons are used or even developed. Finally, Congress has directed the Centers for Disease Control and Prevention to establish a regulatory regime to monitor the location and transfer of hazardous biological agents and to insure that any use of such agents complies with appropriate biosafety requirements.