PatrolSync

Terry v. Ohio (1968)

Reasonable suspicion of criminal activity justifies a brief investigatory stop; a separate, reasonable belief that the person is armed and dangerous additionally justifies a limited pat-down of outer clothing for weapons.

Mapp v. Ohio (1961)

Evidence obtained in violation of the Fourth Amendment is inadmissible in state and federal criminal proceedings under the exclusionary rule.

Katz v. United States (1967)

The Fourth Amendment protects people, not places; a search occurs when the government violates a reasonable expectation of privacy.

Payton v. New York (1980)

Absent exigent circumstances or consent, the Fourth Amendment prohibits warrantless entry into a person's home to make a routine felony arrest.

Rodriguez v. United States (2015)

A traffic stop may not be extended beyond the time needed to complete the stop's mission without independent reasonable suspicion; even a brief extension for a dog sniff violates the Fourth Amendment.

Arizona v. Gant (2009)

Officers may search a vehicle incident to arrest only when the arrestee is unsecured and within reaching distance of the passenger compartment, or when it is reasonable to believe the vehicle contains evidence of the offense of arrest.

Miranda v. Arizona (1966)

Before conducting a custodial interrogation, officers must advise suspects of the right to remain silent, that statements may be used against them, and the right to an attorney—both custody and interrogation must be present to trigger this requirement.

Graham v. Connor (1989)

Force used during a seizure is analyzed under the Fourth Amendment objective reasonableness standard, considering the severity of the crime, the immediate threat posed, and whether the suspect is actively resisting or evading arrest.

Tennessee v. Garner (1985)

Deadly force to prevent the escape of a fleeing suspect is unconstitutional unless the officer has probable cause to believe the suspect poses a significant threat of death or serious physical injury to the officer or others.

Riley v. California (2014)

Officers who lawfully seize a cell phone incident to arrest must generally obtain a search warrant before searching the phone's digital contents; the search-incident-to-arrest exception does not apply to cell phone data.

Illinois v. Gates (1983)

Probable cause from an informant tip is evaluated using the totality of the circumstances, making a practical, common-sense determination that there is a fair probability evidence will be found.

New Jersey v. T.L.O. (1985)

Public school officials may search students without a warrant or probable cause if the search is justified at its inception and reasonably related in scope to the circumstances—a lower standard than for law enforcement.

Missouri v. McNeely (2013)

The natural dissipation of alcohol in the bloodstream does not create a per se exigency justifying warrantless, nonconsensual blood draws in DUI cases; each case requires a totality-of-circumstances analysis.

In re Tony C. (1978)

A lawful detention in California requires specific articulable facts supporting both that some activity relating to crime has occurred or is about to occur and that the person detained is connected to that activity; a hunch or mere curiosity, even in good faith, is insufficient.

People v. Bower (1979)

A person's attempt to avoid contact with police, by itself, does not provide reasonable suspicion to justify a detention; a person is as free to avoid an officer as to avoid any other person, and neither high-crime location nor nighttime hours alone supplies the missing articulable facts.

People v. Ramey (1976)

A warrantless entry into a person's home to make a felony arrest is per se unreasonable under the Fourth Amendment absent exigent circumstances or consent; officers must obtain an arrest warrant (a "Ramey warrant") before entering a suspect's residence to arrest them.

Illinois v. Wardlow (2000)

Unprovoked flight upon noticing police is a relevant factor in the totality-of-circumstances analysis for reasonable suspicion, but it is not, standing alone, automatically sufficient to justify a stop.

Florida v. J.L. (2000)

An anonymous tip that a person is carrying a gun, without more corroboration or indicia of reliability, does not by itself justify a Terry stop and frisk.

Hiibel v. Sixth Judicial District Court of Nevada (2004)

A state stop-and-identify statute requiring a detained person to state their name during a valid Terry stop does not violate the Fourth or Fifth Amendment, but this only applies in states with such laws.

Kyllo v. United States (2001)

Using sense-enhancing technology not in general public use to obtain information about the interior of a home constitutes a Fourth Amendment search requiring a warrant.

Atwater v. City of Lago Vista (2001)

The Fourth Amendment does not prohibit a warrantless custodial arrest for a minor criminal offense, even one punishable only by a fine, when probable cause exists.

Maryland v. Buie (1990)

During an in-home arrest, officers may sweep immediately adjacent spaces as a matter of course; sweeping beyond those areas requires articulable facts that a dangerous person may be present.

Pennsylvania v. Mimms (1977)

An officer may order a driver to exit a lawfully stopped vehicle as a matter of course, without any additional justification.

Maryland v. Wilson (1997)

An officer making a lawful traffic stop may order passengers as well as the driver to exit the vehicle, without additional justification.

Arizona v. Johnson (2009)

During a lawful traffic stop, an officer may conduct a pat-down of a passenger if the officer has reasonable suspicion that the passenger is armed and dangerous.

California v. Acevedo (1991)

Under the automobile exception, police may search a closed container in a vehicle without a warrant if they have probable cause to believe the container holds contraband or evidence.

New York v. Quarles (1984)

Officers may ask questions necessary to protect public safety or officer safety without first providing Miranda warnings; resulting statements and evidence are admissible.

Berkemer v. McCarty (1984)

Routine roadside questioning during a traffic stop does not constitute custodial interrogation requiring Miranda warnings; however, Miranda applies to all custodial interrogations regardless of offense severity.

Horton v. California (1990)

Officers may seize items in plain view without a warrant when lawfully present, the incriminating character is immediately apparent, and they have a lawful right of access to the item; inadvertent discovery is not required.

United States v. Leon (1984)

Evidence seized pursuant to a warrant that is later found invalid is not subject to suppression when officers acted in objectively reasonable good-faith reliance on the warrant; however, good faith does not apply when the affiant misled the magistrate, the magistrate abandoned their role, or the warrant was facially invalid.

Kentucky v. King (2011)

Police-created exigencies do not bar warrantless entry as long as officers created the exigency through conduct that did not itself violate or threaten to violate the Fourth Amendment.

People v. Camacho (2000)

Observations made from a vantage point that an officer reached only through an unconstitutional intrusion into the curtilage of a home cannot support a plain-view search or seizure; the right to be in the location from which the observation is made is a prerequisite of the plain-view doctrine.

People v. Wells (2006)

An anonymous, uncorroborated tip describing a vehicle and reporting a possibly intoxicated driver weaving on the roadway is sufficient to justify a brief investigatory traffic stop, given the serious public-safety risk of impaired driving and the mobile nature of the threat.

People v. Elizalde (2015)

The Miranda exception for routine booking questions is limited to administrative intake questions; questions that officers know or should know are reasonably likely to elicit an incriminating response — such as gang affiliation questions during the booking of a defendant charged with murder — exceed the booking exception and require Miranda advisement.

Hayes v. County of San Diego (2013)

Under California negligence law, an officer's tactical conduct and decisions preceding the use of deadly force are part of the totality of circumstances a court considers in determining whether the force was reasonable; poor pre-shooting tactics can contribute to civil liability even if the shooting itself might be defensible when viewed in isolation.