Warrantless searches in the United States

Aspect of United States law enforcement

Warrantless searches are searches and seizures conducted without court issued search warrants. In the United States, warrantless searches are restricted under the Fourth Amendment to the United States Constitution, part of the Bill of Rights, which states, "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

In the Thirteen Colonies, agents of the British Empire utilized general warrants to authorize searches in the homes of colonists. Such warrants allowed the holder to search any place for any thing at any time. They were viewed as abuses of power, contributing to increased tensions that ultimately led to the American Revolution. The Fourth Amendment barred all warrantless searches and all general warrants; nevertheless, the interpretation and limitations of the Fourth Amendment and the permissibility of warrantless searches under certain circumstances, such as wartime, have been important in the history of executive and judicial power in the United States. During the American Revolutionary War, "the Continental Congress regularly received quantities of intercepted British and Tory mail". See intelligence in the American Revolutionary War. In 1975, the Church Committee, a United States Senate select committee chaired by Frank Church of Idaho, a Democrat, investigated domestic and foreign Cold War area intelligence gathering by the federal government, including warrantless surveillance on anti war advocates inside America. The committee report found the "Americans who violated no criminal law and represented no genuine threat to the 'national security' have been targeted, regardless of the stated predicate. In many cases, the implementation of wiretaps and bugs has also been fraught with procedural violations, even when the required procedures were meager, thus compounding the abuse. The inherently intrusive nature of electronic surveillance, moreover, has enabled the Government to generate vast amounts of information – unrelated to any legitimate governmental interest – about the personal and political lives of American citizens." The "potential criminal liability of the National Security Agency and the Central Intelligence Agency for operations such as SHAMROCK (interception of all international cable traffic from 1945 to 1975) and MINARET (use of watchlists of U. S. dissidents and potential civil disturbers to provide intercept information to law enforcement agencies from 1969 to 1973)" helped persuade president Gerald Ford in 1976 to seek surveillance legislation, which was ultimately enacted as Foreign Intelligence Surveillance Act in 1978. Abuses of power by the federal government led to reform legislation in the 1970s. In its 1985 report "Electronic Surveillance and Civil Liberties", the nonpartisan Congressional Office of Technology Assessment suggested legislation be considered for a surveillance oversight board. Congress disbanded this agency in 1995.

In May 2006, it was revealed that the Bush administration had also been compiling a database of telephone calls, created by the National Security Agency (NSA) with the cooperation of three of the largest telephone carriers in the United States: AT&T, Verizon, and BellSouth. All three companies were paid to provide the information to the NSA. It is speculated that the database contains over 1.9 trillion call detail records of phone calls made after September 11, 2001. The database's existence prompted fierce objection from those who viewed it as a warrantless or illegal search – nevertheless, the collection of such third party information has been authorized by the USA PATRIOT Act, and has been upheld by the courts.

In a 2002 opinion entitled In re: Sealed Case No. 02 001, the United States Foreign Intelligence Surveillance Court of Review examined all the significant appellate decisions. The court noted all the Federal courts of appeal having looked at the issue had concluded that there was such constitutional power. Furthermore, if there was such power, "FISA could not encroach on the president's constitutional power", However, In Re Sealed Case "[took] for granted" that these cases are correct:

The "balancing test drawn from Keith" is a reference to United States v. U. S. District Court, in which the Supreme Court of the United States established a legal test to determine whether the primary use of the warrantless search was to collect foreign intelligence, as per presidential authority, or whether that primary use is to gather evidence for use in a criminal trial.