"Members of Congress and the public have considered ways to prevent the entry and spread of Ebola virus disease (EVD) in the United States. Official recommendations have seemed to conflict at times. In part this reflects the evolution of officials' understanding of this new threat and the scientific and technical aspects of its control. In addition, under the nation's federalist governance structure, the federal and state governments are empowered to take measures to control communicable diseases, and have addressed some aspects of the Ebola threat in varied ways. In the United States and abroad, public concern about the spread of Ebola also may have shaped policymakers' decisions as well. This Congressional Research Service (CRS) report answers common legal and policy questions about the potential introduction and spread of EVD in the United States. Questions and answers are presented in the following topical order: barring travelers from Ebola-stricken countries from coming to the United States, exit procedures upon departure from affected countries in Africa, U.S. laws and procedures involving airlines and other conveyances, identification and screening of passengers arriving from Ebola-affected countries, domestic quarantine and isolation: legal authority and policies."