	Introduction

In the event of a biological attack or the introduction of a highly contagious disease affecting the public, the U.S. health system may take measures to prevent those people infected with or exposed to a disease or a disease-causing biological agent from infecting others. In addition, the federal government may assist with or take over the management of an intrastate incident if requested by a state or if the federal government determines local efforts are inadequate. This report will examine federal and state authority to impose quarantine and isolation measures in order to prevent the spread of infectious disease. Federal Authority

		Quarantine and Isolation

Federal quarantine and isolation authority derives from the Commerce Clause of the U.S. Constitution, which states that Congress shall have the power "[t]o regulate Commerce with foreign Nations, and among the several states." The implementing regulations authorize the quarantine and isolation of individuals in order to prevent the spread of diseases identified in Executive Order 13295. The Director of the CDC is also authorized to take measures as may be necessary to prevent the spread of a communicable disease from one state or possession to any other state or possession if he determines that measures taken by local health authorities are inadequate to prevent the spread of the disease. State Police Powers and Quarantine Authority

While the federal government has authority to authorize quarantine and isolation under certain circumstances, the primary authority for quarantine and isolation exists at the state level as an exercise of the state's police power. Federal authority over interstate and foreign travel is clearly delineated under constitutional and statutory provisions. In a public health emergency, federal, state, and local authorities may overlap. Thus, coordination between the various levels of government would be essential during a widespread public health emergency.
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.