An arrest warrant is a written order from a judge or magistrate that commands the police or other authority to physically take a person accused of a criminal offense into custody. The Fourth Amendment to the United States Constitution requires an arrest warrant to be supported by probable cause—which means there is a reasonable basis to believe the person to be arrested committed a crime.

Arrest warrants protect people from unlawful arrests by requiring the independent review of supporting facts by a person (judge or magistrate) who is not involved in the process of investigating the alleged crime. Arrest warrants also give the accused actual notice of the charge of a criminal offense committed by the accused. Arrest warrants are generally required to take an accused into physical custody unless there is an exception to the warrant requirement—such as when the crime is committed in the presence of the arresting officer.

In Arizona, as in other states, an arrest warrant is a legal document issued by a judge or magistrate that authorizes law enforcement to take an individual into custody on suspicion of a crime. The issuance of an arrest warrant in Arizona is contingent upon the establishment of probable cause, which is a reasonable belief, based on facts and circumstances, that the individual has committed a criminal offense. This requirement is in line with the Fourth Amendment of the U.S. Constitution, which protects individuals against unreasonable searches and seizures. The process ensures that a neutral and detached judicial officer reviews the evidence before an arrest is made, safeguarding individuals from arbitrary law enforcement actions. Exceptions to the warrant requirement do exist, such as when a crime is witnessed by a police officer, but in general, arrest warrants are necessary to provide formal notice to the accused of the charges against them and to ensure that their arrest is lawful.