In United States criminal law, probable cause is the standard by which police authorities have reason to obtain a warrant for the arrest of a suspected criminal or the issuing of a search warrant. It is also the standard by which grand juries issue criminal indictments. The principle behind the standard is to limit the power of authorities to perform random or abusive searches, and to promote lawful evidence gathering and procedural form during criminal arrest and prosecution. The standard also applies to personal or property searches.
Terry v. Ohio, 392 U.S. 1 (1968), was a landmark decision of the Supreme Court of the United States in which the Court ruled that the Fourth Amendment's prohibition on unreasonable searches and seizures is not violated when a police officer stops a suspect on the street and frisks him or her without probable cause to arrest, if the police officer has a reasonable suspicion that the person has committed, is committing, or is about to commit a crime and has a reasonable belief that the person "may be armed and presently dangerous."
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.
A traffic stop, commonly called being pulled over, is a temporary detention of a driver of a vehicle by police to investigate a possible crime or minor violation of law.
Reasonable suspicion is a legal standard of proof in United States law that 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. Caballes, 543 U.S. 405 (2005), was a United States Supreme Court case in which the Court held that the Fourth Amendment is not violated when the use of a drug-sniffing dog during a routine traffic stop does not unreasonably prolong the length of the stop.
United States v. Arvizu, 534 U.S. 266 (2002), is a case in which the Supreme Court of the United States unanimously reaffirmed the proposition that the Fourth Amendment required courts to analyze the reasonableness of a traffic stop based on the totality of the circumstances instead of examining the plausibility of each reason an officer gives for stopping a motorist individually.
Brendlin v. California, 551 U.S. 249 (2007), was a decision by the Supreme Court of the United States that held that all occupants of a car are "seized" for purposes of the Fourth Amendment during a traffic stop, not just the driver.
In United States criminal law, the border search exception is a doctrine that allows searches and seizures at international borders and their functional equivalent without a warrant or probable cause. The doctrine is not regarded as an exception to the Fourth Amendment, but rather to its requirement for a warrant or probable cause. Balanced against the sovereign's interests at the border are the Fourth Amendment rights of entrants. Not only is the expectation of privacy less at the border than in the interior, the Fourth Amendment balance between the interests of the government and the privacy right of the individual is also struck much more favorably to the government at the border. This balance at international borders means that routine searches are "reasonable" there, and therefore do not violate the Fourth Amendment's proscription against "unreasonable searches and seizures".
United States v. Ortiz, 422 U.S. 891 (1975), was a United States Supreme Court case in which the Court held that the Fourth Amendment prevented Border Patrol officers from conducting warrantless, suspicionless searches of private vehicles removed from the border or its functional equivalent.
United States v. Brignoni-Ponce, 422 U.S. 873 (1975), was the case in which the Supreme Court determined it was a violation of the Fourth Amendment for a roving patrol car to stop a vehicle solely on the basis of the driver appearing to be of Mexican descent. A roving patrol car must have articulable facts that allow for an officer to have a reasonable suspicion that the person is carrying illegal aliens beyond their ethnicity. The Court handed down a 9-0 decision that affirmed the Circuit Court's ruling in the case.
United States v. Martinez-Fuerte, 428 U.S. 543 (1976), was a decision of the United States Supreme Court that allowed the United States Border Patrol to set up permanent or fixed checkpoints on public highways leading to or away from the Mexican border and that the checkpoints are not a violation of the Fourth Amendment.
Almeida-Sanchez v. United States, 413 U.S. 266 (1973), was a United States Supreme Court case holding that the warrantless search of an automobile by the United States Border Patrol without a warrant or probable cause violates the Fourth Amendment. The vehicle was stopped and searched for illegal aliens twenty-five miles (40 km) from the Mexican border. The Court approached the search from four views: automobile search, administrative inspection, heavily regulated industry inspection, and border search. As to the validity of the search under the automobile exception, the Court found no justification for the search under the Carroll doctrine because there was no probable cause. As to the validity of the search under various administrative inspection doctrines, the Court found that the officers lacked an area warrant. As to the validity of the heavily regulated industry inspection, the Court found that the doctrine is not applicable to traveling on a state highway. As to the validity of a border search, the Court found that the site of the stop and the entirety of the road on which the stop occurred was too far from the border to be considered a border search.
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.
Heien v. North Carolina, 574 U.S. 54 (2014), is a decision by the United States Supreme Court, ruling that a police officer's reasonable mistake of law can provide the individualized suspicion required by the Fourth Amendment to the United States Constitution to justify a traffic stop. The Court delivered its ruling on December 15, 2014.
Rodriguez v. United States, 575 U.S. ___ (2015), was a United States Supreme Court case which analyzed whether police officers may extend the length of a traffic stop to conduct a search with a trained detection dog. In a 6–3 opinion, the Court held that officers may not extend the length of a traffic stop to conduct a dog sniff unrelated to the original purpose of the stop. However, the Court remanded the case to the United States Court of Appeals for the Eighth Circuit to determine whether the officer's extension of the traffic stop was independently justified by reasonable suspicion. Some analysts have suggested that the Court's decision to limit police authority was influenced by ongoing protests in Ferguson, Missouri.
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.
United States v. Sharpe 470 U.S. 675 (1985) was an important decision of the U.S. Supreme Court in which the Court explained how long police are permitted to stop vehicles as part of an investigatory stop before violating the Fourth Amendment. A seven-member majority of the Court determined the twenty minute stop in this case was legal, so the government won. However, the Court declined to adopt a bright line rule, deciding instead that "common sense and ordinary human experience must govern over rigid criteria." The Court announced that the rule for determining whether a detention is too long will depend on whether the police "diligently pursued" an investigation to quickly confirm or dispel their suspicions. The Court clarified that judges should avoid "unrealistic second-guessing" of police and should take into account "swiftly developing situation[s]." Sharpe has been frequently cited, and is the framework used to challenge unduly prolonged police stops in thousands of criminal cases.
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.
