Warrantless means that government officers carry out a search or arrest without a warrant or any other legal authorization. The requirement of a warrant serves to protect individuals’ privacy interests against unreasonable governmental intrusion. Evidence obtained without a warrant are per se unreasonably seized and should be excluded unless it falls under the exceptions that permit a warrantless search and arrest. The Supreme Court in Katz v. United States, 389 U.S. 347 (1967) held that “searches conducted outside the judicial process, without prior approval are prohibited under the Fourth Amendment, with a few detailed exceptions.” The following are exceptions that permit warrantless search:

Plain View Doctrine:  

Private view: If an officer is lawfully on the premises or stops the vehicle for a lawful purpose, and “the incriminating character of the item is immediately apparent,” the officers can seize that in plain view, even if it is not on the warrant list. See Horton v. California, 496 U.S. 128 (1990).

Public view: Since individuals have no reasonable expectation of privacy of content exposed to the public, items in public view may be seized without a warrant.

Exigent Circumstances

Officers will take immediate actions to secure a warrant or they may search warrantless if they believe that failing to do so will cause the destruction of evidence, threaten public safety, or cause a suspect to flee. See Illinois v. McArthur, 531 U.S. 326 (2001).

If the exigency is caused by officers, then the search violates the Fourth Amendment. Once the exigency ends, warrantless search must end. See Kentucky v. King, 563 U.S. 131 (2011).

Hot pursuit: Officers can arrest and search individuals who are suspected of committing a felony. For the pursuit, officers can enter any property to search and seize evidence without warrants. If the crime is not a felony, the exception cannot be applied. See Welsh v. Wisconsin, 466 U.S. 740 (1984).

Emergency situations: Emergency situations are applied to avoid the destruction of evidence, protect officers or the public, or inhibit suspects from fleeing. Whether an emergency exists is determined objectively from the officer's judgment. 


If the officer has probable cause to believe that an automobile contains evidence of a crime or contraband, they can search automobiles, including the trunk and luggage, or other containers which may reasonably contain evidence or contraband, without a warrant. See Caroll v. United States, 267 U.S. 132 (1925)

Scope: Motor vehicles, trailers, boats, airplanes, and other transportation.

Consent: A third party with possessory rights of the property may have authority to consent to a search if consent is voluntarily given. 

Voluntary: If the consent was given under threat, then it’s invalid. To determine whether the consent was valid, courts may evaluate the circumstances when consent was made. For instance, if the officer acquired the consent because they erroneously stated that they have a warrant, the consent given in reliance on that statement does not constitute consent. See Bumper v. North Carolina, 391 U.S. 543, 549 (1968).

Failing to disclose the right to withhold consent will not cause the consent invalid. See Schneckloth v. Bustamonte, 412 U.S. 218, 233 (1973).

Authority: The property should be legally owned, occupied or jointly controlled by the third party. See Frazier v. Cupp, 394 U.S. 731, 740 (1969).

Scope: Usually warrantless automobile searches are limited to consent, but sometimes may extend to reasonable suspicion. See Florida v. Jimeno, 500 U.S. 248, 252 (1991).

Administrative Search

Administrative searches are different from criminal searches,as administrative searches aim to search evidence of a regulatory violation or for public interest. See Camara v. Mun. Court of San Francisco, 387 U.S. 523, 533 (1967). There are some administrative searches which don't need warrants, like vehicle checkpoints and roadblocks, factory or inventory searches, detention of a traveler, institutional residential settings, cause of fire searches, and so on.

Stop and frisk: If officers have reasonable suspicion that a crime is occurring, they can stop a suspect for weapons to ensure their safety.


A search incident leading to an arrest may not require a warrant. If the officer just searches a suspect’s immediate surroundings to prevent destruction of evidence or secure safety of themselves or nearby people. See Warden v. Hayden, 387 US. 294 (1967).

Legitimacy: The arrest must be lawful and officers have reasonable belief the automobile contains evidence of the offense of arrest. If the search precedes the arrest, then it’s illegal.

Time & area: The search must be contemporaneous in time and place with the arrest.

Scope: The person and their arm-span no matter if it's an open or closed space, locked or unlocked.

Exception: Officers need exigent circumstances or search warrants to search the contents of a cell phone.

[Last updated in June of 2022 by the Wex Definitions Team