No single figure in 20th-century American history inspires such opposing opinions as J. Edgar Hoover, the iconic first Director of the Federal Bureau of Investigation. In his time, he was arguably the most powerful non-elected figure in the federal government.

Few things have colored Hoover's reputation quite like COINTELPRO, which has become the FBI's most notorious operation, one that still has lasting ramifications. From 1956-1971, the FBI waged a secret war in America through a series of projects against groups believed to be potentially subversive, including various people and organizations involved in women's rights, civil rights, Native American rights, anti-war groups, and even groups that supported animal rights. In many instances, these projects involved covert and illegal surveillance of people who had done nothing to break the law but were willing to speak out about injustice. The FBI labeled these people as subversive and began not just to watch them but to act against them. In some cases, these actions involved harassment and intimidation of suspected subversives and burglary to seize files and other documents. In a few cases, the FBI is suspected of committing perjury to discredit groups or individuals, and it has even been suggested that the FBI was involved, indirectly, in people's deaths.

This vast operation was virtually unknown until one activist group carried out its own burglary of an FBI field office in Pennsylvania, during which files detailing some COINTELPRO operations were stolen and sent to news agencies. The Washington Post was initially the only American newspaper to run a story, featuring it in a front-page article, and within a year, FBI Director J. Edgar Hoover announced that COINTELPRO was over.