Federal Bureau of Investigation FBI Law and Legal Definition

The Federal Bureau of Investigation (FBI) is the principal investigative arm of the United States Department of Justice. It evolved from an unnamed force of Special Agents appointed on July 26, 1908 by then-Attorney General Charles J. Bonaparte to be the investigative force of the Department of Justice. It has the authority and responsibility to investigate specific crimes assigned to it. The FBI also is authorized to provide other law enforcement agencies with cooperative services, such as fingerprint identification, laboratory examinations, and police training.

The FBI is charged with upholding the law through the investigation of violations of federal criminal law; protecting the United States from foreign intelligence and terrorist activities; and providing leadership and law enforcement assistance to federal, state, local, and international agencies. The FBI's investigative functions fall into the categories of applicant matters; civil rights; counterterrorism; foreign counterintelligence; organized crime/drugs; violent crimes and major offenders; and financial crime.

The FBI is headed by a Director who is appointed by the President and confirmed by the Senate for a term not to exceed ten years. The FBI is headquartered in Washington D.C. The offices and divisions at FBI Headquarters provide program direction and support to 56 field offices, approximately 400 satellite offices known as resident agencies, four specialized field installations, and over 45 foreign liaison posts known as Legal Attaches.