warrant, in law, written order by an official of a court directed to an officer. The search warrant and the warrant of arrest are the most frequently used types. Warrants of attachment order the seizure of a defendant's goods pending trial or judicial determination of ownership and in certain other cases. Warrants are usually issued by a judge or court clerk. They are directed to sheriffs, marshals, constables, and other officers of the peace. The strictest compliance with legal forms and rules for serving a warrant is ordinarily necessary if it is to be effective.

search warrant, in law, written order by an official of a court authorizing an officer to search in a specified place for specified objects and to seize them if found. The objects sought may be stolen goods or physical evidences of the commission of crime (e.g., narcotics). The Fourth Amendment to the U.S. Constitution, which protects against unreasonable searches and seizures, provides, in effect, that a search warrant may be issued only on oath or affirmation that a crime was probably committed. In Mapp v. Ohio (1961) the U.S. Supreme Court mandated states to exclude from trial evidence obtained in illegal searches, such as those without a proper warrant. This "exclusionary rule" has been the subject of great controversy and subsequent litigation. In recent years, the Supreme Court has narrowed the scope of the rule, in many circumstances permitting the introduction of any evidence gathered in "good faith." Courts have ruled that a wiretap and the use of a thermal-imaging device to examine a private home from a public street constitutes a search that requires a warrant. Warrants are not required for the gathering of evidence in some circumstances. These exceptions include evidence gathered after a lawful arrest, inspections by customs or border officials, searches made with the suspect's consent, searches of items in plain view, and searches of the belongings of secondary students on school property.

In law, authorization in writing empowering a person to perform an act or execute an office. Arrest warrants are necessary (except in certain circumstances) for an arrest to be considered legal. Search warrants enh1 the holder to enter and search a property. Both are classes of judicial warrants. To obtain them, a complainant must provide an affidavit setting forth facts sufficient to satisfy the belief that a crime has been committed and that the accused is the guilty party (or, in the case of the search warrant, that the place to be searched will yield the expected evidence). Nonjudicial warrants include tax warrants (which provide the authority to collect taxes) and land warrants (which enh1 the holder to a specific tract of public land).

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