09/22/2026
Case laws are like the bible of law enforcement. It explains what you can and cannot do.
Terry v. Ohio, 392 U.S. 1 (1968)
Reasonable suspicion permits a brief investigative detention; a frisk requires reasonable belief the person is armed and dangerous.
Illinois v. Wardlow, 528 U.S. 119 (2000)
Unprovoked flight in a high-crime area can contribute to reasonable suspicion, but context matters.
Whren v. United States, 517 U.S. 806 (1996)
An objectively valid traffic violation can support a stop even when the officer has another investigative motive.
Heien v. North Carolina, 574 U.S. 54 (2014)
A reasonable mistake of law can, under certain circumstances, provide reasonable suspicion for a stop.
Rodriguez v. United States, 575 U.S. 348 (2015)
A traffic stop generally cannot be prolonged beyond its traffic mission to conduct a dog sniff unless reasonable suspicion develops.
Illinois v. Caballes, 543 U.S. 405 (2005)
A properly conducted exterior narcotics-detection dog sniff during a lawful traffic stop generally isn’t a Fourth Amendment search, provided it doesn’t prolong the stop.
Arizona v. Johnson, 555 U.S. 323 (2009)
During a lawful traffic stop, officers may conduct a weapons frisk when they reasonably suspect the person is armed and dangerous.
Michigan v. Long, 463 U.S. 1032 (1983)
Under appropriate circumstances, officers may conduct a protective search of areas of a vehicle where a weapon could be placed or hidden.
Pennsylvania v. Mimms, 434 U.S. 106 (1977)
Officers may order the driver out of a lawfully stopped vehicle.
Maryland v. Wilson, 519 U.S. 408 (1997)
Officers may order passengers out during a lawful traffic stop.
Arizona v. Gant, 556 U.S. 332 (2009)
Limits searches of vehicles incident to arrest. Don’t automatically search the passenger compartment simply because an occupant was arrested.
United States v. Ross, 456 U.S. 798 (1982)
With probable cause to search a vehicle, the automobile exception can permit searching areas/containers where the object of the search could reasonably be located.
California v. Acevedo, 500 U.S. 565 (1991)
Probable cause concerning a container in a vehicle can permit a warrantless search of that container under the automobile exception.
Carroll v. United States, 267 U.S. 132 (1925)
Foundation of the automobile exception.
United States v. Place, 462 U.S. 696 (1983)
Important foundation for canine detection and temporary detention of property.
Illinois v. Gates, 462 U.S. 213 (1983)
Totality-of-the-circumstances approach for determining probable cause from informant information.
Schneckloth v. Bustamonte, 412 U.S. 218 (1973)
Voluntary consent does not require officers to advise the person that they have a right to refuse.
Miranda v. Arizona, 384 U.S. 436 (1966)
Custodial interrogation generally triggers Miranda protections.
Berkemer v. McCarty, 468 U.S. 420 (1984)
Ordinary roadside questioning during a traffic stop generally isn’t automatically Miranda custody.
New York v. Quarles, 467 U.S. 649 (1984)
Public-safety exception to Miranda when officers reasonably need immediate answers to address an ongoing danger.
Riley v. California, 573 U.S. 373 (2014)
Generally requires a warrant to search digital information on a cell phone seized incident to arrest.
Graham v. Connor, 490 U.S. 386 (1989)
Use-of-force claims are generally evaluated under the Fourth Amendment’s objective-reasonableness standard.
Scott v. Harris, 550 U.S. 372 (2007)
is a major case for officers dealing with vehicle pursuits and use of force.
A fleeing motorist’s dangerous driving can create an immediate threat to officers and the public that may justify significant force to end the pursuit.
