During the period of U.S. combat involvement in the Vietnam War, there was considerable argument about progress among the Department of Defense under Robert McNamara, the CIA, and, to some extent, the intelligence staff of Military Assistance Command Vietnam. In general, the military was consistently more optimistic than the CIA. Sam Adams, a junior CIA analyst with responsibilities for estimating the actual damage to the enemy, eventually resigned from the CIA, after expressing concern to Director of Central Intelligence Richard Helms with estimates that were changed for interagency and White House political reasons. Adams afterward wrote the book War of Numbers.
Things came to a head in the mid-1970s, around the time of Watergate. A dominant feature of political life during that period were the attempts of Congress to assert oversight of the U.S. Presidency and the executive branch of the U.S. government. Revelations about past CIA activities, such as assassinations and attempted assassinations of foreign leaders (most notably Fidel Castro and Rafael Trujillo) and illegal domestic spying on U.S. citizens, provided the opportunities to increase Congressional oversight of U.S. intelligence operations.
Hastening the CIA's fall from grace were the burglary of the Watergate headquarters of the Democratic Party by ex-CIA agents, and President Richard Nixon's subsequent attempt to use the CIA to impede the FBI's investigation of the burglary. In the famous "smoking gun" recording that led to President Nixon's resignation, Nixon ordered his chief of staff, H. R. Haldeman, to tell the CIA that further investigation of Watergate would "open the whole can of worms" about the Bay of Pigs Invasion of Cuba. In this way Nixon and Haldemann ensured that the CIA's No. 1 and No. 2 ranking officials, Richard Helms and Vernon Walters, communicated to FBI Director L. Patrick Gray that the FBI should not follow the money trail from the burglars to the Committee to Re-elect the President, as it would uncover CIA informants in Mexico. The FBI initially agreed to this due to a long-standing agreement between the FBI and CIA not to uncover each other's sources of information. Though within a couple of weeks the FBI demanded this request in writing, and when no such formal request came, the FBI resumed its investigation into the money trail. Nonetheless, when the smoking gun tapes were made public, damage to the public's perception of CIA's top officials, and thus to the CIA as a whole, could not be avoided.
In 1973, then-Director of Central Intelligence (DCI) James R. Schlesinger commissioned reports -- known as the "Family Jewels" -- on illegal activities by the Agency. In December 1974, investigative journalist Seymour Hersh broke the news of the "Family Jewels" (after it was leaked to him by DCI William Colby) in a front-page article in The New York Times, claiming that the CIA had assassinated foreign leaders, and had illegally conducted surveillance on some 7,000 U.S. citizens involved in the antiwar movement (Operation CHAOS). The CIA had also experimented on people, who unknowingly took LSD (among other things).
Congress responded to the disturbing charges in 1975, investigating the CIA in the Senate via the Church Committee, chaired by Senator Frank Church (D-Idaho), and in the House of Representatives via the Pike Committee, chaired by Congressman Otis Pike (D-NY). In addition, President Gerald Ford created the Rockefeller Commission, and issued an executive order prohibiting the assassination of foreign leaders.
During the investigation, Schlesinger's successor as DCI, William Colby, testified before Congress on 32 occasions in 1975, including about the "Family Jewels". Colby later stated that he believed that providing Congress with this information was the correct thing to do, and ultimately in the CIA's own interests. As the CIA fell out of favor with the public, Ford assured Americans that his administration was not involved: "There are no people presently employed in the White House who have a relationship with the CIA of which I am personally unaware."
Repercussions from the Iran-Contra affair arms smuggling scandal included the creation of the Intelligence Authorization Act in 1991. It defined covert operations as secret missions in geopolitical areas where the U.S. is neither openly nor apparently engaged. This also required an authorizing chain of command, including an official, presidential finding report and the informing of the House and Senate Intelligence Committees, which, in emergencies, requires only "timely notification."