In This Article Expand or collapse the "in this article" section Search Warrants

  • Introduction
  • General Overviews
  • Historical Background of the Warrant Requirement
  • Search Warrant Requirement and Controversy
  • Search Warrant Exceptions

Criminology Search Warrants
Naoki Kanaboshi
  • LAST REVIEWED: 27 June 2022
  • LAST MODIFIED: 27 June 2022
  • DOI: 10.1093/obo/9780195396607-0322


A search warrant is an order issued by the court that permits and commands the police to conduct a search and seize the evidence of a crime. In the United States, it is considered that except for certain limited exceptions, the Fourth Amendment to the Constitution of the United States requires the police to obtain a search warrant before conducting a search. The Fourth Amendment provides, “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.” To obtain a search warrant from a court, the government official (typically a police/law enforcement officer) must establish, under oath, that there is probable cause to believe that evidence of a crime will be found at the place(s) they seek to search. If a fair and neutral judicial officer (typically a judge or magistrate) is convinced that probable cause exists, they may issue the search warrant. The police may search the location particularly specified in the warrant for the items particularly specified in the warrant. However, a search warrant is not always required when police conduct some investigative activities. A search warrant is required only when the police activities satisfy the legal concept of a “search.” If the police conduct is not a search, a search warrant is not required. Moreover, even for a search, the Fourth Amendment allows a search without a search warrant under certain circumstances. Thus the established rule is that a search generally requires a search warrant. But there has been academic debate on whether the Fourth Amendment really requires a warrant in the first place. This debate occurs due to the text of the Fourth Amendment. While the second half of the Amendment, “no Warrants shall issue . . . ,” certainly discusses a search warrant, the Fourth Amendment itself does not specifically say that a search requires a search warrant. Thus, some scholars asserted, the Amendment only requires that a search be “reasonable,” and the failure to obtain a search warrant does not by itself make the search unreasonable. This entry focus on search warrants in the United States. The “Supreme Court” in this entry refers to the US Supreme Court.

General Overviews

The Fourth Amendment requires that a warrant may be issued only upon the establishment of probable cause under oath and affirmation, that the warrant describes the place to be searched and things to be seized, and that the warrant must be issued by a judicial officer, such as a judge or magistrate. In terms of the formatting, the states are free to use their own style. A jurisdiction’s warrant may reflect additional federal or state law requirements for a search warrant. The website of United States Courts shows the empty (unfilled) federal search warrant and application form. The US Department of Justice website shows an example of a real federal search warrant used in its anthrax case, along with the filled application form for a search warrant, the police’s sworn statement (affidavit) that demonstrates the presence of probable cause, and the return (inventory) of seized items during the search with this warrant (none). As for state level, Rosenblatt 2004 shows New York’s forms. Notable treatises on criminal procedure (including search warrants) include LaFave, et al. 2017 and Dressler and Michaels 2017. Perhaps the most cited law review article regarding the Fourth Amendment is Amsterdam 1974. Van Duizend, et al. 1985 shows a detailed account of the search warrant process, including perspectives about the application process by police, prosecutors, and judges.

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