The history of the Federal Bureau of Investigation (FBI), apart from its role in fighting crime, shows that its powers of surveillance of subversives and political dissidents has grown in response to real and supposed threats to national security. However, the FBI's success in providing domestic security has sometimes been marred by excessive use of its powers and violations of civil liberties. These violations, such as the "Enemies List" compiled at the request of President Richard Nixon during the Vietnam War, have occurred especially when driven by political purposes. Because of the vigilance required for protecting American citizens against attacks in an age of terrorism, the FBI's investigatory powers have once more been expanded. As in America's past wars, many have voiced warnings that civil liberties must not be sacrificed for security.

First created in 1908 as the investigative division of...