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A warrant is "[a] writ that authorizes or directs an act.[1]


Traditionally, the warrant requirement of the Fourth Amendment in the criminal setting has been viewed as a protective measure, placing the authority to issue a warrant with a “neutral and detached” judicial officer who can assess whether the police have probable cause to make an arrest, to conduct a search, or to seize materials.[2] “There is . . . a presumption of validity with respect to the affidavit supporting [a] search warrant.”[3]

In instances where the interests of the public outweigh those of private individuals, however, the U.S. Supreme Court has recognized “specifically established exceptions” to the warrant and probable cause requirements of the Fourth Amendment.[4]

Intelligence gathering[]

The extent to which the Fourth Amendment warrant requirement applies to the government’s collection of information for intelligence gathering and other purposes unrelated to criminal investigations is unclear. Although the surveillance of wire or oral communications for criminal law enforcement purposes was held to be subject to the warrant requirement of the Fourth Amendment in 1967,[5] neither the Supreme Court nor Congress sought to regulate the use of such surveillance for national security purposes at that time.

Several years later, the Supreme Court invalidated warrantless electronic surveillance of domestic organizations for national security purposes, but indicated that its conclusion might differ if the electronic surveillance targeted foreign powers or their agents.[6] A lower court has since upheld the statutory scheme governing the gathering of foreign intelligence information against a Fourth Amendment challenge, despite an assumption that orders issued pursuant to the statute might not constitute “warrants” for Fourth Amendment purposes.[7] The Supreme Court has not yet directly addressed the issue. However, even if the warrant requirement was found not to apply to searches for foreign intelligence or national security purposes, such searches would presumably be subject to the general Fourth Amendment “reasonableness” test.[8]

Documents held by third parties[]

In contrast with its rulings on surveillance, the Supreme Court has not historically applied the protections of the Fourth Amendment to documents held by third parties. In 1976, it held that financial records in the possession of third parties could be obtained by the government without a warrant.[9] Later, it likewise held that the installation and use of a pen register does not constitute a Fourth Amendment search.[10] The reasoning was that individuals have a lesser expectation of privacy with regard to information held by third parties.


  1. Society of American Archivists, Glossary of Archival and Records Terminology (full-text).
  2. See Coolidge v. New Hampshire, 403 U.S. 443, 450 (1971) (full-text); see also Warden Md. Penitentary v. Hayden, 387 U.S. 294, 301-02 (1967) (full-text).
  3. Franks v. Delaware, 438 U.S. 154, 171 (1978) (full-text).
  4. Camara v. Municipal Court, 387 U.S. 523, 539-40 (1967) (full-text).
  5. Katz v. United States, 389 U.S. 347, 353 (1967) (full-text), overruling Olmstead v. United States, 277 U.S. 438 (1928) (full-text).
  6. United States v. U.S. District Court, 407 U.S. 297, 313-14, 321-24 (1972) (full-text) (also referred to as the Keith case, so named for the District Court judge who initially ordered disclosure of unlawful warrantless electronic surveillance to the defendants). See also In re Directives, 551 F.3d 1004, 1011 (Foreign Intell. Surveillance Ct. Rev. 2008) (full-text) (holding that the foreign intelligence surveillance of targets reasonably believed to be outside of the U.S. qualifies for the “special needs” exception to the warrant requirement).
  7. In re Sealed Case, 310 F.3d 717, 738-46 (Foreign Intell. Surveillance Ct. Rev. 2002) (full-text).
  8. The “general reasonableness” or “totality-of-the circumstances” test requires a court to determine the constitutionality of a search or seizure “by assessing, on the one hand, the degree to which [a search or seizure] intrudes upon an individual’s privacy and, on the other, the degree to which it is needed for the promotion of legitimate governmental interests.” Samson v. California, 547 U.S. 843, 848 (2006) (full-text).
  9. United States v. Miller, 425 U.S. 435 (1976) (full-text).
  10. Smith v. Maryland, 442 U.S. 735, 745-46 (1979) (full-text).

See also[]