Terry v. Ohio, 392 U.S. 1 (1968), was a landmark U.S. Supreme Court decision in which the court ruled that it is constitutional for American police to "stop and frisk" a person they reasonably suspect to be armed and involved in a crime. Specifically, the decision held that a police officer does not violate the Fourth Amendment to the U.S. Constitution's prohibition on unreasonable searches and seizures when questioning someone even though the officer lacks probable cause to arrest the person, so long as the police officer has a reasonable suspicion that the person has committed, is committing, or is about to commit a crime. The court also ruled that the police officer may perform a quick surface search of the person's outer clothing for weapons if they have reasonable suspicion that the person stopped is "armed and presently dangerous." This reasonable suspicion must be based on "specific and articulable facts," and not merely upon an officer's hunch.
A Terry stop in the United States allows the police to briefly detain a person based on reasonable suspicion of involvement in criminal activity. Reasonable suspicion is a lower standard than probable cause which is needed for arrest. When police stop and search a pedestrian, this is commonly known as a stop and frisk. When police stop an automobile, this is known as a traffic stop. If the police stop a motor vehicle on minor infringements in order to investigate other suspected criminal activity, this is known as a pretextual stop. Additional rules apply to stops that occur on a bus.
Reasonable suspicion is a legal standard of proof that in United States law is less than probable cause, the legal standard for arrests and warrants, but more than an "inchoate and unparticularized suspicion or 'hunch'"; it must be based on "specific and articulable facts", "taken together with rational inferences from those facts", and the suspicion must be associated with the specific individual. If police additionally have reasonable suspicion that a person so detained is armed and dangerous, they may "frisk" the person for weapons, but not for contraband like drugs. However, if the police develop probable cause during a weapons frisk, they may then conduct a full search. Reasonable suspicion is evaluated using the "reasonable person" or "reasonable officer" standard, in which said person in the same circumstances could reasonably suspect a person has been, is, or is about to be engaged in criminal activity; it depends upon the totality of circumstances, and can result from a combination of particular facts, even if each is individually innocuous.
Illinois v. Gates, 462 U.S. 213 (1983), is a Fourth Amendment case. Gates overruled Aguilar v. Texas and Spinelli v. United States, thereby replacing the Aguilar–Spinelli test for probable cause with the "totality of the circumstances" test.
United States v. Montoya De Hernandez, 473 U.S. 531 (1985), was a U.S. Supreme Court case regarding the Fourth Amendment's border search exception and balloon swallowing.
Illinois v. Caballes, 543 U.S. 405 (2005), is a decision by the Supreme Court of the United States in which the Court held that the use of a drug-sniffing police dog during a routine traffic stop does not violate the Fourth Amendment to the U.S. Constitution, even if the initial infraction is unrelated to drug offenses.
Illinois v. Wardlow, 528 U.S. 119 (2000), is a case decided before the United States Supreme Court involving U.S. criminal procedure regarding searches and seizures.
Aguilar v. Texas, 378 U.S. 108 (1964), was a decision by the United States Supreme Court, which held that "[a]lthough an affidavit supporting a search warrant may be based on hearsay information and need not reflect the direct personal observations of the affiant, the magistrate must be informed of some of the underlying circumstances relied on by the person providing the information and some of the underlying circumstances from which the affiant concluded that the informant, whose identity was not disclosed, was credible or his information reliable." Along with Spinelli v. United States (1969), Aguilar established the Aguilar–Spinelli test, a judicial guideline for evaluating the validity of a search warrant based on information provided by a confidential informant or an anonymous tip. The test developed in this case was subsequently rejected and replaced in Illinois v. Gates, 462 U.S. 213 (1983).
Whren v. United States, 517 U.S. 806 (1996), was a unanimous United States Supreme Court decision that "declared that any traffic offense committed by a driver was a legitimate legal basis for a stop."
Pennsylvania v. Mimms, 434 U.S. 106 (1977), is a United States Supreme Court criminal law decision holding that a police officer ordering a person out of a car following a traffic stop and conducting a pat-down to check for weapons did not violate the Fourth Amendment to the United States Constitution.
The stop-question-and-frisk program, or stop-and-frisk, in New York City, is a New York City Police Department (NYPD) practice of temporarily detaining, questioning, and at times searching civilians and suspects on the street for weapons and other contraband. This is what is known in other places in the United States as the Terry stop. The rules for the policy are contained in the state's criminal procedure law section 140.50 and based on the decision of the US Supreme Court in the case of Terry v. Ohio.
Steagald v. United States, 451 U.S. 204 (1981), is a United States Supreme Court case which held that, based on the Fourth Amendment, a police officer may not conduct a warrantless search of a third party's home in an attempt to apprehend the subject of an arrest warrant, absent consent or exigent circumstances.
Estate of Thornton v. Caldor, Inc., 472 U.S. 703 (1985), was a United States Supreme Court case in which the Court held that a state statute providing employees with an absolute right not to work on their chosen Sabbath violates the Establishment Clause of the First Amendment.
Ybarra v. Illinois was a decision of the U.S. Supreme Court which ruled that a warrant can not be used to search an unnamed individual unless the warrant mentions that unnamed parties are involved or exigent circumstances are shown to exist.
Navarette v. California, 572 U.S. 393 (2014), was a case in which the United States Supreme Court clarified when police officers may make arrests or conduct temporary detentions based on information provided by anonymous tips. In 2008, police in California received a 911 call that a pickup truck was driving recklessly along a rural highway. Officers spotted a truck matching the description provided in the 911 call and followed the truck for five minutes, but did not observe any suspicious behavior. Nevertheless, officers conducted a traffic stop and discovered 30 pounds (14 kg) of marijuana in the truck. At trial, the occupants of the car argued that the traffic stop violated the Fourth Amendment of the United States Constitution, because the tip was unreliable, and officers did not personally observe criminal activity. Writing for a majority of the Court, Justice Clarence Thomas held that the 911 call was reliable, and that officers need not personally observe criminal activity when acting upon information provided by an anonymous 911 call.
In the law, the totality of the circumstances test refers to a method of analysis where decisions are based on all available information rather than bright-line rules. Under the totality of the circumstances test, courts focus "on all the circumstances of a particular case, rather than any one factor". In the United States, totality tests are used as a method of analysis in several different areas of the law. For example, in United States criminal law, a determination about reasonable suspicion or probable cause is based on a consideration of the totality of the circumstances.
Kansas v. Glover, 589 U.S. ___ (2020), was a United States Supreme Court case in which the Court held when a police officer lacks information negating an inference that the owner is driving a vehicle, an investigative traffic stop made after running a vehicle's license plate and learning that the registered owner's driver's license has been revoked is reasonable under the Fourth Amendment.
Maryland v. Wilson, 519 U.S. 408 (1997), was a decision by the Supreme Court of the United States. The Court held that officers could order passengers out a car during a traffic stop, extending Pennsylvania v. Mimms.
United States v. Ramirez, 523 U.S. 65 (1998), was a case before the United States Supreme Court in which the Court held that property damage during a no-knock warrant is irrelevant as long as law enforcement has reasonable suspicion that knocking and announcing would be a dangerous move.
Alabama v. White, 496 US 325 (1990), is a U.S. Supreme Court case involving the Fourth Amendment. The majority opinion ruled that anonymous tips can provide reasonable suspicion for a traffic stop provided that police can factually verify the circumstances asserted by the tip.
