The 1975-76 Church Committee congressional hearings probed widespread intelligence abuses by the FBI, CIA, IRS and NSA. Headed by Senator Frank Church (D-Idaho) in the wake of the Watergate scandal, the committee exposed how under the guise of national security agencies spied on American citizens for political purposes during the Kennedy, Johnson and Nixon administrations.

While the hearings focused on the FBI and CIA, they also catapulted the National Security Agency (NSA) from the shadows of the intelligence underworld to the national stage. The hearings revealed how the NSA set up secret projects code-named "Shamrock" and "Minaret" to collect international and domestic communications. In Project Shamrock, the major communication companies of the day -- Western Union, RCA Global and ITT World Communications -- provided the NSA access to their international message traffic, from which the NSA extracted telegrams containing the names provided to them by the FBI, CIA and other sources. Church said the three-decade long program "certainly appears to violate section 605 of the Communications Act of 1934 as well as the Fourth Amendment of the Constitution."

Church also described how the NSA's program morphed, creeping into dangerous domestic territory over time: "At the outset, the purpose apparently was only to extract international telegrams relating to certain foreign targets. Later the government began to extract the telegrams of certain U.S. citizens." Shamrock spanned three decades, and by the time of the hearings, it was estimated that the NSA was analyzing 150,000 messages per month.

The committee also discovered abuses in Project Minaret, a sister program to Project Shamrock. In Project Minaret, the NSA added Vietnam War protestors to its watch list at the request of the U.S. Army, which was concerned about the heavily attended 1967 "March on the Pentagon" protest. The list scooped up notable protesters including actress Jane Fonda, singer Joan Baez and Dr. Martin Luther King, Jr. Then-NSA Deputy Director Benson Buffham stated, "It appeared to us that we were going to be requested to do far more than we had done before."

The Church Committee's revelation that the NSA had caught American citizens in their dragnets raised a question: Does the Fourth Amendment -- with its protections against "unreasonable searches and seizures" and requirement for "probable cause" -- apply to domestic spying for national security purposes?

Discovery of the various abuses fueled fears of still greater abuses. Sen. Walter Mondale (D-Minn.) worried that the NSA "could be used by President 'A' in the future to spy upon the American people, to chill and interrupt political dissent." To prevent these fears from evolving into a reality, the committee determined that oversight beyond the executive level was necessary.

Congress responded to the committee's findings by passing the Foreign Intelligence Surveillance Act (FISA) of 1978, which created the secret Foreign Intelligence Surveillance Court (FISC) to issue warrants for domestic eavesdropping. In recognition of national security imperatives, Congress allowed the proceedings of the FISA court to be kept secret. Seven judges, from different regions of the country, are appointed by the chief justice of the Supreme Court for seven-year terms.

For decades, the FISA court operated in the shadows. But in December 2005, The New York Times moved it into the limelight. It published an article describing how shortly after 9/11, President Bush had authorized the NSA to eavesdrop without warrants inside the United States, bypassing the FISA court; in a press conference four days after the article was published, the president maintained that the program was limited to calls from a suspected terrorist abroad to an individual inside the U.S. Experts quoted in the Times article questioned whether the president's program violated the FISA law. Some critics have questioned the usefulness of the FISA court itself, labeling it a "rubber stamp for the government." They claim that thousands of warrants are approved by the court every year, and only a handful of requests are rejected.

An exclusive inside look at the FISA court was provided to FRONTLINE correspondent Hedrick Smith by James Baker, the chief Justice Department liaison with the FISA court. In his interview with Smith, Baker describes a court that handles thousands of warrant applications each year, hearing requests for surveillance from the FBI and other agencies around a large table in a simple but highly secure conference room on the sixth floor of the Department of Justice.

Baker disputes two major criticisms of the FISA -- one, that it is a rubber stamp, and two, that it moves too slowly to have satisfied the needs of the NSA after 9/11. He gives a detailed account of the process of considering a warrant in what he calls a "robust back and forth" between judges and Baker's office. Baker says there is a lot more give and take than the public perceives and asserts that approval for a wiretap can be obtained in a matter of minutes, rebutting the criticism that it takes too long to get a warrant for eavesdropping in cases that require immediate action.

Katelyn Epsley-Jones and Christina Frenzel were research assistants on Spying on the Home Front.

• Related Links
• Interview with James Baker
  Baker heads the Justice Department's Office of Intelligence Policy and Review (OIPR), which is responsible for preparing and filing all applications for domestic surveillance under the Foreign Intelligence Surveillance Act (FISA). Here, he details his interactions with the court and rebuts some of the criticisms about the process.
• Can FISA Keep Up With the Terrorism Threat?
  Experts from FRONTLINE's report weigh in on the debate over whether FISA is flexible enough to counter the modern terrorism threat.
• FISA Orders 1979-2005
  This chart, compiled by the Electronic Privacy Information Center, breaks down the number of FISA applications presented, approved and rejected since 1979. These numbers are taken from annual reports filed to Congress by the Justice Department; the original reports (since 1996) are available on the DOJ Web site.