The Federal Bureau of Investigation FBI

The Justice Department had no detectives of its own until 1908, when Attorney General Charles Bonaparte, blocked by Congress from borrowing Secret Service agents, hired a small force of investigators on July 26 of that year. The Bureau of Investigation grew through Prohibition and the gangster era and took its present name in 1935 under J. Edgar Hoover, who ran it for forty-eight years, built it into a national institution, and accumulated power that alarmed presidents of both parties. After his death Congress limited the Director to a single ten-year term, the only such limit on any federal law enforcement chief.

The FBI is both a law enforcement agency and an intelligence service, a dual role that distinguishes it from police forces in most democracies. On the criminal side it investigates violations of more than two hundred federal statutes: terrorism, espionage, cyber intrusions, public corruption, civil rights crimes, organized crime, white-collar fraud, violent crime that crosses state lines, and kidnapping. On the intelligence side it leads domestic counterintelligence and counterterrorism, operating under the Attorney General's guidelines and, for foreign-power surveillance, under warrants from the Foreign Intelligence Surveillance Court. It does not prosecute. It hands cases to U.S. Attorneys.

About 38,000 people work for the Bureau, roughly 13,000 of them special agents, the rest analysts, scientists, linguists, and support staff. Fifty-five field offices and hundreds of smaller resident agencies cover the country, and legal attache offices sit in more than sixty embassies abroad. The FBI Laboratory at Quantico, Virginia, shares a campus with the academy that trains new agents and, through the National Academy, thousands of state and local police. The Bureau runs the national fingerprint and criminal history databases and the background check system for gun purchases.

The FBI's independence from the White House has been the central question about it since Hoover. The ten-year term, the Attorney General's guidelines, and post-Watergate norms were all meant to keep the Bureau from becoming a political instrument. Those arrangements have been strained repeatedly since 2016, with directors dismissed before their terms ended, investigations of presidential candidates and presidents themselves, and in 2025 a new director who had publicly pledged to overhaul an agency he called politicized. Whether the Bureau is a check on power or a tool of it is a question both parties have asked, from opposite directions, in the same decade.