From the Summary: "In the wake of increasing fears about the spread of highly contagious diseases, federal, state, and local governments have become increasingly aware of the need for a comprehensive public health response to such events. An effective response could include the quarantine of persons exposed to infectious biological agents that are naturally occurring or released during a terrorist attack, the isolation of infected persons, and the quarantine of certain cities or neighborhoods. The public health authority of the states derives from the police powers granted by their constitutions and reserved to them by the Tenth Amendment to the U.S. Constitution. The authority of the federal government to prescribe quarantine and other health measures is based on the Commerce Clause, which gives Congress exclusive authority to regulate interstate and foreign commerce. Thus, state and local governments have the primary authority to control the spread of dangerous diseases within their jurisdictions, and the federal government has authority to quarantine and impose other health measures to prevent the spread of diseases from foreign countries and between states. In addition, the federal government may assist state efforts to prevent the spread of communicable diseases if requested by a state or if state efforts are inadequate to halt the spread of disease. This report provides an overview of federal and state public health laws as they relate to the quarantine and isolation of individuals and a discussion of constitutional issues that may be raised should individual liberties be restricted in a quarantine or isolation situation."
CRS Report for Congress, RL33201