Federal Bureau of Investigation

In 1896, the National Bureau of Criminal Identification was founded, which provided agencies across the country with information to identify known criminals. The 1901 assassination of President William McKinley created a perception that America was under threat from anarchists. The Departments of Justice and Labor had been keeping records on anarchists for years, but President Theodore Roosevelt wanted more power to monitor them.

J. Edgar Hoover served as FBI Director from 1924 to 1972, a combined 48 years with the BOI, DOI, and FBI. He was chiefly responsible for creating the Scientific Crime Detection Laboratory, or the FBI Laboratory, which officially opened in 1932, as part of his work to professionalize investigations by the government. Hoover was substantially involved in most major cases and projects that the FBI handled during his tenure. But as detailed below, his proved to be a highly controversial tenure as Bureau Director, especially in its later years. After Hoover's death, the Congress passed legislation that limited the tenure of future FBI Directors to ten years.

According to Douglas M. Charles, the FBI's "sex deviates" program began on April 10, 1950, when J. Edgar Hoover forwarded the White House, U.S. Civil Service Commission, and branches of the armed services a list of 393 alleged federal employees who were allegedly arrested in Washington, D.C., since 1947, on charges of "sexual irregularities". On June 20, 1951, Hoover expanded the program by issuing a memo establishing a "uniform policy for the handling of the increasing number of reports and allegations concerning present and past employees of the United State Government who assertedly [sic] are sex deviates." The program was expanded to include non-government jobs. According to Athan Theoharis, "In 1951 he [Hoover] had unilaterally instituted a Sex Deviates program to purge alleged homosexuals from any position in the federal government, from the lowliest clerk to the more powerful position of White house aide." On May 27, 1953, Executive Order 10450 went into effect. The program was expanded further by this executive order by making all federal employment of homosexuals illegal. On July 8, 1953, the FBI forwarded to the U.S. Civil Service Commission information from the sex deviates program. In 1977–1978, 300,000 pages, collected between 1930 to the mid-1970s, in the sex deviates program were destroyed by FBI officials.

From the end of the 1980s to the early 1990s, the FBI reassigned more than 300 agents from foreign counter-intelligence duties to violent crime, and made violent crime the sixth national priority. With reduced cuts to other well-established departments, and because terrorism was no longer considered a threat after the end of the Cold War, the FBI assisted local and state police forces in tracking fugitives who had crossed state lines, which is a federal offense. The FBI Laboratory helped develop DNA testing, continuing its pioneering role in identification that began with its fingerprinting system in 1924.

After Congress passed the Communications Assistance for Law Enforcement Act (CALEA, 1994), the Health Insurance Portability and Accountability Act (HIPAA, 1996), and the Economic Espionage Act (EEA, 1996), the FBI followed suit and underwent a technological upgrade in 1998, just as it did with its CART team in 1991. Computer Investigations and Infrastructure Threat Assessment Center (CITAC) and the National Infrastructure Protection Center (NIPC) were created to deal with the increase in Internet-related problems, such as computer viruses, worms, and other malicious programs that threatened US operations. With these developments, the FBI increased its electronic surveillance in public safety and national security investigations, adapting to the telecommunications advancements that changed the nature of such problems.

For over 40 years, the FBI crime lab in Quantico had believed that lead alloys used in bullets had unique chemical signatures. It was analyzing the bullets with the goal of matching them chemically, not only to a single batch of ammunition coming out of a factory, but also to a single box of bullets. The National Academy of Sciences conducted an 18-month independent review of comparative bullet-lead analysis. In 2003, its National Research Council published a report whose conclusions called into question 30 years of FBI testimony. It found the analytic model used by the FBI for interpreting results was deeply flawed, and the conclusion, that bullet fragments could be matched to a box of ammunition, was so overstated that it was misleading under the rules of evidence. One year later, the FBI decided to stop conducting bullet lead analyses.

The FBI's chief tool against organized crime is the Racketeer Influenced and Corrupt Organizations (RICO) Act. The FBI is also charged with the responsibility of enforcing compliance of the United States Civil Rights Act of 1964 and investigating violations of the act in addition to prosecuting such violations with the United States Department of Justice (DOJ). The FBI also shares concurrent jurisdiction with the Drug Enforcement Administration (DEA) in the enforcement of the Controlled Substances Act of 1970.

A March 2007 report by the inspector general of the Justice Department described the FBI's "widespread and serious misuse" of national security letters, a form of administrative subpoena used to demand records and data pertaining to individuals. The report said that between 2003 and 2005, the FBI had issued more than 140,000 national security letters, many involving people with no obvious connections to terrorism.

According to The Washington Post, the FBI "is building a vast repository controlled by people who work in a top-secret vault on the fourth floor of the J. Edgar Hoover Building in Washington. This one stores the profiles of tens of thousands of Americans and legal residents who are not accused of any crime. What they have done is appear to be acting suspiciously to a town sheriff, a traffic cop or even a neighbor.

FBI Directors are appointed (nominated) by the President of the United States and must be confirmed by the United States Senate to serve a term of office of ten years, subject to resignation or removal by the President at his/her discretion before their term ends. Additional terms are allowed following the same procedure.