Awarrant is generally an order that serves as a specific type ofauthorization, that is, awrit issued by a competent officer, usually ajudge ormagistrate, that permits an otherwise illegal act that would violateindividual rights in order to enforce the law and aid in investigations; affording the person executing the writ protection fromdamages if the act is performed.

A warrant is usually issued by acourt and is directed to asheriff, aconstable, or apolice officer. Warrants normally issued by a court includesearch warrants,arrest warrants, andexecution warrants.

• Arrest warrant, issued by a judge to detain someone
• Execution warrant, writ issued by a judge authorizing the death of someone
• Possessory warrant, a civil writ issued by a judge ordering property searched for, then delivered to a named person
• Search warrant, a writ issued by a judge allowing law enforcement to look inside a property
• Warrant of committal, issued by a judge ordering enforcement of a previous order against an uncooperative person or corporation
• Warrant of delivery, a civil writ issued by a judge ordering property delivered to a named person
• Warrant of execution, a writ issued by a judge allowing law enforcement officers to seize property
• Warrant of possession, an Australian judge ordered to terminate of a residential real estate tenancy

In theUnited Kingdom, senior public appointments are made by warrant under theroyal sign-manual, the personalsignature of themonarch, on the recommendation of the government. In an interesting survival from medieval times, these warrants abate (lose their force) on the death of the sovereign if they have not already been executed. This particularly applied to death warrants in the days whenEngland authorizedcapital punishment.

Perhaps the most well-known example of this occurred on 17 November 1558, when England was under the rule of a Catholic queen,Mary I, daughter ofHenry VIII and the Spanish CatholicCatherine of Aragon. SeveralProtestants convicted ofheresy had been condemned to die. They were tied to stakes inSmithfield, an open market area in centralLondon, and the firewood bundles were about to be lit, when a royal messenger rode up to announce thatMary I had died: the warrants for their death had lost their force. The first formal act of Mary's successor, the ProtestantElizabeth I, daughter of Henry VIII andAnne Boleyn, was to decline to re-issue the warrants; the Protestants were released a few weeks later.

For many years, the English, later British, government had used a "general warrant" to enforce its laws. These warrants were broad in nature and did not have specifics as to why they were issued or what the arrest was being made for. A general warrant placed almost no limitations on the search or arresting authority of a soldier or sheriff. This concept had become a serious problem when those in power issued general warrants to have their enemies arrested when no wrongdoing had been done. TheParliament of Great Britain passed theRevenue Act 1767 (7 Geo. 3. c. 46)^[1][2] which reaffirmed the legality ofwrits of assistance, or generalsearch warrants, and gave customs officials broad powers to search houses and businesses for smuggled goods.^[3] This law was one of the key acts of Great Britain which led to theAmerican Revolution,^{[citation needed]} and is the direct reason that theAmerican Founding Fathers ensured that general warrants would be illegal in the United States by ratifying theFourth Amendment to the U.S. Constitution in 1791.

Under theFourth Amendment to the United States Constitution a warrant is broadly required, which particularly describes the place to be searched, and the persons, or things, to be seized; no warrants may be issued withoutprobable cause, and support by testimony before a judge.

The courts have recognized manywarrantless searches, including exceptions for routine administrative or inventory searches, searches made under exigent circumstances, and searches made with consent.

A typical arrest warrant in theUnited States will take the approximate form of: "This Court orders theSheriff or Constable to find the named person, wherever he may be found, and deliver said person to the custody of the Court." Generally, a U.S. arrest warrant must contain thecaption of the court issuing the warrant, the name (if known) of the person to be arrested, the offense charged, the date of issue, the officer(s) to whom the warrant is directed, and the signature of the magistrate.^[4]

Warrants may also be issued by othergovernment entities, includinglegislatures, since most have thepower to compel the attendance of their members. When a legislature issues a warrant, it is called acall of the house.

The person being investigated, arrested, or having their property seized, pursuant to a warrant is given a copy of the warrant at the time of its execution.^{[citation needed]}

• Arrest Warrant of 11 April 2000 case, a case in public international law involving diplomatic immunity
• Warrant canary, a method used by Internet service providers to inform their customers that the provider has been served with a secret government subpoena
• Quo warranto, a writ requiring the person to whom it is directed to show what authority they have for exercising some right or power (or "franchise") they claim to hold

• Craies, William Feilden (1911)."Warrant" .Encyclopædia Britannica. Vol. 28 (11th ed.). pp. 327–327.
• UK appointments made by warrant under the Royal sign manual—from theLondon Gazette