The intelligence services of the United States, like their counterparts in most countries, exist principally to serve the needs of the executive authority. The US intelligence apparatus, however—unlike that of most countries—also makes a large part of its output available to the legislative branch.
It has not always been so. Before the mid-1970s, Congress was given relatively little intelligence, and access to it was limited. The Congressional investigations of US intelligence agencies in 1975-76 by the Church and Pike Committees fundamentally altered this situation. For the first time, voluminous amounts of intelligence were shared with the investigating committees. When permanent oversight committees were subsequently established in both Houses, the trend toward ever-increasing disclosure continued. Ground rules to govern intelligence-sharing were agreed to shortly after the oversight committees began operations, but none were written down, and over time these understandings often gave way in the continuing tussle between the overseers and the overseen. Twenty years later, the system still operates without formal rules of the road.
In 1992, Congress amended the National Security Act of 1947 to spell out specific duties for the Director of Central Intelligence (DCI), among them the obligation to provide intelligence “where appropriate, to the Senate and House of Representatives and the committees thereof.” In enacting this language, however, Congress shed no light on what it regarded as an “appropriate” level of intelligence support for itself. Nor did the executive branch use the occasion to specify what it thought was “appropriate” to provide to Congress.