The FBI, or Federal Bureau of Investigation, is the investigative arm of the U.S. Department of Justice and the nation’s primary investigative and domestic intelligence agency. First established in 1908, the FBI has often been criticized for violating the civil rights of law-abiding U.S. citizens, even as its role expanded to include domestic and international terrorism.

Bureau of Investigation

By the first years of the 20th century, it had become clear that the U.S. Department of Justice lacked sufficient resources to investigate violations of the law across a sprawling, quickly growing nation.

In 1908, President Theodore Roosevelt, who had taken office after a deranged anarchist assassinated President William McKinley in 1901, gave his approval for his attorney general, Charles J. Bonaparte (a grandnephew of Napoleon) to bypass Congress and form his own investigative squad.

In a memo dated July 26, 1908, Bonaparte stated that a “regular force of special agents” would handle all investigative matters from U.S. attorneys. This force, which included some former Secret Service agents, would become the nucleus of the new Bureau of Investigation.

Renamed the U.S. Bureau of Investigation in 1932, the bureau wouldn’t receive its current name, Federal Bureau of Investigation, until 1935.

Mann Act

The new bureau took the lead on investigating violations of the Mann Act (known as the “White Slave Traffic Act”), passed in 1910, which barred the transportation of people across state lines for the purposes of engaging in sexual activity.

During World War I, passage of the Espionage Act of 1917 led the bureau to launch its first nationwide domestic surveillance program, including wiretapping conversations and opening the mail of suspected radicals.

J. Edgar Hoover

Fears of communism on the rise in the United States grew into a full-fledged “Red Scare” by early 1920, after a series of bombing attacks by anarchists on national leaders.

On the authority of Attorney General A. Mitchell Palmer, the young Justice Department lawyer J. Edgar Hoover directed the bureau’s agents to sweep up between 6,000 and 10,000 Americans, in mass arrests that became known as the “Palmer Raids.”

Though the raids initially made headlines for their success, the bureau was almost immediately criticized for violating the civil liberties of thousands of people. Hoover’s star rose quickly at the Justice Department, however, and in 1921 he was named the Bureau of Investigation’s assistant director.

Three years later, Attorney General Harlan Fiske Stone tapped Hoover to serve as acting director on an interim basis. Just 29 years old at the time, Hoover would remain in the director’s post for the next 48 years.


The arrival of Prohibition fueled an unprecedented crime wave in the United States, with bootleggers and gangsters wreaking havoc in cities across the country.

To combat this, Hoover set out to reform the Bureau of Investigation and make it into a more professional, effective force. He fired sub-par investigators and those he saw as political appointees, and put in place a rigorous hiring process and strict code of conduct for all agents.

The bureau had put out its first “Wanted” poster in 1919, and by the late 1920s similar posters were circulating in the United States, Canada and Europe. They later spread worldwide, and in 1950 the FBI would debut its now-famous “Ten Most Wanted Fugitives” list.

The FBI’s profile rose as Prohibition gave way to the Great Depression, thanks to its pursuit of well-known gangsters, bank robbers and other notorious criminals, including John Dillinger, Bonnie Parker and Clyde Barrow (aka Bonnie and Clyde), George “Machine Gun” Kelly and Alvin Karpis.

The exploits of the so-called “G-men” and their colorful outlaw targets even made it to Hollywood, and by the 1940s Hoover had become a household name.

World War II

With the outbreak of World War II, the FBI began investigating threats to national security, including American Nazi, fascist and communist groups.

President Franklin D. Roosevelt tasked the FBI with overseeing intelligence operations in the entire Western Hemisphere, which the bureau did through the Special Intelligence Service (SIS), set up in June 1940.

Under FDR, the powers of Hoover’s FBI to run secret intelligence operations against America’s suspected enemies expanded greatly—a directive Hoover would cite for the rest of his life. In the lead-up to U.S. entry into World War II, the FBI compiled a list of German, Japanese and Italian aliens in the United States whom they considered a threat to the country.

Within 72 hours after the U.S. declared war, agents had moved to arrest more than 3,800 people.

Yet Hoover opposed FDR’s decision to detain more than 100,000 Japanese Americans in internment camps; he wanted people investigated and imprisoned (if necessary) based on their allegiance to the enemy, not merely their race.

Dawn of the Cold War

By the mid-1950s, as the Cold War heated up, the bureau launched a program of covert operations aimed at suspected Communist and socialist groups within the United States.

Convinced that communism was behind the nation’s growing civil rights movement, Hoover made its leaders the focus of some of the FBI’s fiercest scrutiny. Most notoriously, the bureau tapped the phones of the rising young minister Martin Luther King Jr., gathering information about his supposed communist associations and his numerous extramarital affairs.

Hoover also kept close tabs on the private life of President John F. Kennedy, and clashed fiercely with his brother and attorney general, Robert F. Kennedy.

With passage of the Civil Rights Act of 1964, the FBI received jurisdiction over many cases involving segregation and voting rights violations, among other issues. While continuing to monitor civil rights leaders and organizations, the bureau also launched a counterintelligence program against the Ku Klux Klan, which was gaining strength in opposition to the civil rights movement.

End of the Hoover Era

During his 48-year tenure as FBI director, Hoover’s reputation for having access to so much compromising information about so many people ensured that no president was willing or able to remove him from his post.

After Hoover died in his sleep in 1972, President Richard M. Nixon said in a press conference: “Every American, in my opinion, owes J. Edgar Hoover a great debt for building the FBI into the finest law enforcement organization in the entire world.”

Because of how powerful Hoover had become, the Department of Justice took steps to rein the bureau in, including limiting the directorship to a single 10-year term, to be appointed by the president and confirmed by the Senate.

At the same time, the FBI played a pivotal role in the mounting Watergate scandal, with deputy director Mark Felt becoming a key source for the Washington Post reporters writing about the role played by the Nixon administration in the break-in at Democratic National Committee (DNC) headquarters. (Felt’s identity as “Deep Throat,” though suspected, was only confirmed after his death in 2008.)

FBI and Terrorism

In the 1980s, aside from its continuing efforts to combat Soviet Union espionage, the FBI focused much of its work on global drug trafficking and white-collar crime.

But the bombing of Pan Am Flight 103 over Lockerbie, Scotland, in 1988 and especially the 1993 bombing of the World Trade Center pushed Islamic terrorism to the forefront of the bureau’s national security concerns. Domestic attacks, like the Oklahoma City bombing and the deadly Unabomber attacks, also helped make counterterrorism one of the FBI’s highest priorities by the mid-1990s.

In the wake of the devastating terrorist attacks of September 11, 2001, the Patriot Act greatly expanded the FBI’s powers to surveil both U.S. citizens and foreign residents. Director Robert Mueller, who took office just a week before 9/11 and headed up the massive investigation that followed the attacks, would become the longest-serving director since J. Edgar Hoover, and the only one since Hoover to complete the maximum 10-year term.

FBI and Civil Liberties

Concerns about the FBI’s overreach into the lives of ordinary citizens have dogged the bureau since the Palmer raids in 1920, and only increased during the Hoover era. In 1967, the Supreme Court placed limits on the FBI’s abilities to legally surveil citizens by ruling in Katz v. United States that the Fourth Amendment protection against “unreasonable searches and seizures” covered electronic wiretaps.

Legal battles over the FBI’s methods of gathering evidence have continued in the post 9/11 era. But despite criticism by the American Civil Liberties Union (ACLU) and others, the Patriot Act gave way to the Freedom Act in 2015, which retained many of the powers of surveillance given to the FBI by the earlier act.

2016 Presidential Election

During the 2016 presidential election, the FBI investigated Democratic presidential candidate Hillary Clinton’s use of a private email server during her tenure as secretary of state.

After announcing in July that she had been cleared of criminal impropriety, FBI Director James Comey made headlines again, writing to Congress three weeks before the election to reveal that new emails had been discovered that could be linked to the case.

After Clinton lost the election to Donald Trump, Comey made even bigger waves when he confirmed that the FBI was investigating possible collusion between the Trump campaign and Russian officials who wanted to help Trump win the election.

In May 2017, Trump fired Comey, who claimed (in a detailed memo that was leaked to the press shortly after he was fired) that the president had asked him to drop an inquiry related to Russian involvement in the election. That same month, the Department of Justice appointed Mueller, the former FBI director, as special counsel in charge of an investigation into Russia’s alleged interference in the 2016 election.


A Brief History,
Tim Weiner, Enemies: A History of the FBI (New York: Random House, 2012).
A history of the FBI and former American presidents, MPR News.
The Justice Department, The Oxford Guide to the United States Government.
The FBI’s Role in National Security, Council on Foreign Relations.

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