Government Surveillance: What the Law Allows

For decades the FBI and the NSA conducted surveillance in the name of national security without warrants, from wiretaps on Martin Luther King Jr. to copies of Americans' international telegrams. After the Supreme Court required warrants for domestic security surveillance in 1972 and the Church Committee exposed the abuses, Congress passed the Foreign Intelligence Surveillance Act in 1978. It requires an order from a special court of federal district judges, meeting in secret, based on probable cause that the target is a foreign power or its agent. Critics say the court approves nearly every application, and a 2019 inspector general report found serious errors in FBI applications to surveil a former Trump campaign adviser. Supporters say judicial review is a real check that did not exist before 1978.

Much government data gathering never goes before a judge. The FBI can demand phone, internet, financial, and credit records with national security letters, usually with a gag order. Prosecutors use grand jury and administrative subpoenas for records held by companies, which under the third-party doctrine get less constitutional protection. Banks file millions of suspicious activity reports with the Treasury each year. Customs officers search travelers' phones at the border. Intelligence agencies collect abroad under Executive Order 12333 with no court involvement, and agencies have bought location and other data from commercial brokers. The House passed a bill in April 2024 to require a warrant for such purchases, but it did not become law.

The central fight is whether agents should need a warrant to search intelligence databases for Americans' communications. A coalition of progressives and conservatives says yes, arguing that the searches amount to warrantless access to Americans' private messages. Intelligence officials, the FBI, and many national security lawmakers say warrants would slow urgent searches for victims of hacking or terrorism and that internal approvals and audits are enough. Others want limits on data purchases, stronger outside advocates in the FISA Court, and more transparency. The independent privacy board, which shaped earlier reforms, lost its quorum when the President removed three members in January 2025. Each expiration date forces Congress to revisit the balance.

Section 702, added in 2008, lets the government collect the communications of non-Americans reasonably believed to be abroad from U.S. phone and internet companies, under annual certifications approved by the FISA Court rather than individual warrants. It covers more than 200,000 targets a year, and officials say it supplies much of the intelligence in the President's Daily Brief. Because foreigners communicate with Americans, those messages are collected too, and the FBI can search the data using Americans' identifiers, searches that courts and reviews found were sometimes improper. A 2024 law renewed the authority for two years. After the House rejected an extension on June 11, 2026, the authority lapsed on June 12, the first lapse since 2008, but collection continues under certifications that run until March 17, 2027.

In criminal investigations, federal agents generally need a warrant from a judge, issued on probable cause and describing what will be searched, before searching a home, reading stored email, or tapping a phone. Evidence gathered illegally is usually excluded from trial. Courts allow searches without a warrant with consent, in emergencies, during arrests, for vehicles, for brief stops on reasonable suspicion, and at the border. Officers need a warrant to enter a home to make an arrest, and the use of administrative immigration warrants, signed by officials rather than judges, to enter homes was disputed in 2025 and 2026. The Supreme Court has required warrants to search cell phones and to obtain historical location records from phone companies.

Six weeks after the attacks, Congress passed the USA PATRIOT Act, which made it easier to use FISA when criminal charges were also possible, expanded national security letters, and broadened the power to obtain business records under Section 215. In secret, the President authorized warrantless surveillance outside FISA, revealed in 2005, and from 2006 the NSA used Section 215 to collect records of nearly all Americans' phone calls. After Edward Snowden disclosed the program in 2013, an appeals court found it exceeded the law, and the Privacy and Civil Liberties Oversight Board found it had not made a concrete difference in stopping any attack. The USA FREEDOM Act ended it in 2015, and Section 215 expired in 2020.