Published video explainers connected to Case Law Academy case studies.
Michigan Department of State Police v. Sitz
For police officers, Michigan Department of State Police v. Sitz means that DUI checkpoints are not automatically unconstitutional just because officers lack individualized suspicion for each driver stopped. A checkpoint may be lawful if it is structured, limited, and aimed at roadway safety rather than general crime control.
Brady v. Maryland
Brady v. Maryland requires prosecutors to disclose material evidence favorable to the accused when it bears on guilt or punishment. The rule protects the fairness of criminal trials and applies regardless of whether the prosecution acted in good or bad faith.
Pearson v. Callahan
Pearson v. Callahan changed qualified immunity procedure. The Court held that judges are no longer required to decide the constitutional violation question before asking whether the law was clearly established.
Monell v. Department of Social Services of the City of New York
Monell v. Department of Social Services of the City of New York: in Monell, the Supreme Court overruled part of Monroe v. Pape and held that local governments are 'persons' under § 1983. Municipalities may be liable when official policy or custom causes a constitutional violation, but not simply because they employ the person who committed the violation.
Carroll v. United States
Carroll v. United States, 267 U.S. 132 (1925), upheld a warrantless search of an automobile during Prohibition because officers had probable cause to believe it carried illegal liquor. The decision established the automobile exception: mobility can make a warrant impractical, but probable cause remains required.
Berghuis v. Thompkins
In Berghuis v. Thompkins, the Supreme Court held that a suspect who has received and understood Miranda warnings must clearly invoke the right to remain silent. Remaining mostly silent during an interrogation does not, by itself, require police to stop questioning, and an uncoerced answer can amount to an implied waiver.
City of Canton v. Harris
City of Canton v. Harris held that a municipality can be liable under § 1983 for failure to train police employees, but only when the failure reflects deliberate indifference to constitutional rights and causes the injury. The case is a foundation of modern Monell municipal-liability doctrine.
Katz v. United States
In Katz v. United States, 389 U.S. 347 (1967), the Supreme Court reversed a conviction based on warrantless recordings from a public phone booth. The Court held that the Fourth Amendment protects people, not places, and that electronic surveillance of a private conversation can be a search even without physical trespass.
Herring v. United States
In Herring v. United States, 555 U.S. 135 (2009), the Supreme Court held that evidence found after an arrest based on an outdated warrant record did not have to be suppressed. The exclusionary rule turns on whether suppression would deter sufficiently culpable police conduct, not on every negligent recordkeeping mistake.
Griffin v. Wisconsin
In Griffin v. Wisconsin, the Supreme Court upheld a warrantless search of a probationer's home under a Wisconsin regulation requiring reasonable grounds and supervisor approval. The Court treated probation supervision as a special need beyond ordinary law enforcement, allowing a limited departure from the usual warrant and probable-cause rules.
Graham v. Connor
Graham v. Connor established that police excessive-force claims during arrests, stops, or seizures are governed by Fourth Amendment objective reasonableness. The rule focuses on the facts confronting officers at the scene, including severity of the suspected offense, immediate safety threats, and resistance or flight, while avoiding hindsight and subjective-intent tests.
City of Houston v. Hill
In City of Houston v. Hill, 482 U.S. 451 (1987), the Supreme Court struck down a Houston ordinance that criminalized interrupting police officers. The Court held that the ordinance swept too broadly into protected speech and gave police too much discretion to arrest people for verbal criticism or challenge.
United States v. Leon
United States v. Leon, 468 U.S. 897 (1984), held that the exclusionary rule generally does not bar evidence seized by officers who reasonably rely in good faith on a search warrant later found invalid. The decision created a major Fourth Amendment doctrine while preserving suppression for serious police misconduct or plainly unreliable warrants.
Riley v. California
Riley v. California, 573 U.S. 373 (2014), held that the Fourth Amendment generally requires police to get a warrant before searching digital information on a cell phone seized incident to arrest. The Court balanced law enforcement needs against the uniquely broad privacy interests in modern phones and left room for exigent circumstances in urgent cases.
Heien v. North Carolina
In Heien v. North Carolina, the Supreme Court held that an officer's objectively reasonable mistake about the law can still create reasonable suspicion for a traffic stop under the Fourth Amendment. The stop began with one nonworking brake light, even though state law was later read to require only one working stop lamp.
Miranda v. Arizona
In Miranda v. Arizona, the Supreme Court held that statements from custodial interrogation generally cannot be used unless law enforcement first provides warnings protecting the privilege against self-incrimination and the right to counsel, and any waiver is voluntary, knowing, and intelligent.
Arizona v. Gant
Arizona v. Gant held that police cannot automatically search a vehicle just because they arrested a recent occupant. A search incident to arrest is allowed only if the arrestee could access the vehicle at the time of the search, or if officers reasonably believe the vehicle contains evidence of the offense of arrest.
Edwards v. Arizona
Edwards v. Arizona held that once a person in custody invokes the Miranda right to counsel, police cannot initiate further custodial interrogation unless counsel is provided or the person initiates further communication and validly waives the right.
County of Los Angeles v. Mendez
In County of Los Angeles v. Mendez, the Supreme Court rejected the Ninth Circuit's provocation rule. The Court held that a prior Fourth Amendment violation does not automatically convert a later reasonable use of force into unconstitutional excessive force, though the prior violation may still support damages under proximate-cause principles.
Carpenter v. United States
In Carpenter v. United States, the Supreme Court held that law enforcement's acquisition of extensive historical cell-site location information is a Fourth Amendment search. A lower Stored Communications Act order was not enough; a probable-cause warrant is generally required for this kind of detailed location tracking.
United States v. Jones
United States v. Jones held that the government's installation and use of a GPS tracker on a vehicle was a Fourth Amendment search. The decision emphasized that Katz privacy analysis did not replace the older rule protecting people against physical government trespass on persons, houses, papers, and effects to obtain information.
Plumhoff v. Rickard
Plumhoff v. Rickard held that officers did not violate the Fourth Amendment when they used deadly force to stop a person fleeing police in a high-speed chase that endangered the public. The Court also held the officers were protected by qualified immunity in any event.
Terry v. Ohio
Terry v. Ohio, 392 U.S. 1 (1968), upheld a limited stop and frisk based on reasonable suspicion and safety concerns. The decision recognized that stops and frisks are Fourth Amendment events, but allowed a narrow weapons pat-down without probable cause when specific facts make the intrusion reasonable.
Whren v. United States
In Whren v. United States, the Supreme Court unanimously held that a traffic stop supported by probable cause does not violate the Fourth Amendment just because officers may have had an additional investigative motive. The decision affirmed an objective Fourth Amendment rule for traffic stops.
Saucier v. Katz
Saucier v. Katz held that qualified immunity in excessive force cases is not identical to the Fourth Amendment reasonableness inquiry. Courts must separately consider whether the alleged facts show a constitutional violation and whether that right was clearly established in the specific circumstances.
New Jersey v. T.L.O.
In New Jersey v. T.L.O., the Supreme Court held that public school officials are bound by the Fourth Amendment, but student searches in school are governed by a special reasonableness standard. Schools do not usually need a warrant or probable cause.
Mapp v. Ohio
In Mapp v. Ohio, 367 U.S. 643 (1961), the Supreme Court reversed Dollree Mapp's conviction and held that evidence obtained through unconstitutional searches and seizures cannot be used in state criminal trials. The decision made the exclusionary rule binding on state and local law enforcement through the Fourteenth Amendment.
Harlow v. Fitzgerald
Harlow v. Fitzgerald, 457 U.S. 800 (1982), created the modern objective qualified immunity test: federal officials performing discretionary duties are protected from damages unless they violate clearly established rights a reasonable official would have known.
Tidwell v. City and County of Denver
Tidwell v. City and County of Denver is a Colorado police-pursuit case explaining that a chase can legally count as a pursuit even without lights and siren, and that emergency-signal requirements can affect governmental immunity.
Scott v. Harris
Scott v. Harris is the Supreme Court's major police-pursuit force case. It explains when force used to end a dangerous high-speed chase can be reasonable under the Fourth Amendment.
Tennessee v. Garner
Tennessee v. Garner sets the constitutional standard for deadly force against fleeing suspects.