The Fourth Amendment to the United States Constitution is part of the Bill of Rights. It prohibits unreasonable searches and seizures. In addition, it sets requirements for issuing warrants: warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized.
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.
Search and seizure is a procedure used in many civil law and common law legal systems by which police or other authorities and their agents, who, suspecting that a crime has been committed, commence a search of a person's property and confiscate any relevant evidence found in connection to the crime.
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 it is not unconstitutional 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 it is not a violation of the Fourth Amendment to the U.S. Constitution's prohibition on unreasonable searches and seizures when a police officer stops a suspect on the street and questions him or her even without probable cause to arrest, 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.
A traffic stop, commonly referred to as 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.
In the United States, the exclusionary rule is a legal rule, based on constitutional law, that prevents evidence collected or analyzed in violation of the defendant's constitutional rights from being used in a court of law. This may be considered an example of a prophylactic rule formulated by the judiciary in order to protect a constitutional right. The exclusionary rule may also, in some circumstances at least, be considered to follow directly from the constitutional language, such as the Fifth Amendment's command that no person "shall be compelled in any criminal case to be a witness against himself" and that no person "shall be deprived of life, liberty or property without due process of law."
United States v. Place, 462 U.S. 696 (1983), was a decision by the Supreme Court of the United States which held that a sniff of luggage in a public place, by a police dog specially trained to detect the odor of narcotics, was not a "search" under the meaning of the Fourth Amendment to the United States Constitution. The Court reasoned that the sniff of a dog is sui generis, intended to disclose only the presence or absence of narcotics. Because a dog sniff is such a limited test, the Court carved out this exception from the broad category of "searches" for which a warrant is generally required.
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.
Atwater v. Lago Vista, 532 U.S. 318 (2001), was a United States Supreme Court decision which held that a person's Fourth Amendment rights are not violated when the subject is arrested for driving without a seatbelt. The court ruled that such an arrest for a misdemeanor that is punishable only by a fine does not constitute an unreasonable seizure under the Fourth Amendment.
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.
Suppression of evidence is a term used in the United States legal system to describe the lawful or unlawful act of preventing evidence from being shown in a trial. This could happen for several reasons. For example, if a judge believes that the evidence in question was obtained illegally, the judge can rule that it not be shown in court. It could also refer to a prosecutor improperly or intentionally hiding evidence that does not go with their case and could suggest or prove to the judge or jury that the defendant is not guilty or that (s)he is legally obligated to show the defense. In the latter case, this would be a violation of the 5th amendment to the United States Constitution. Also Rule 3.8 of the ABA Model Rules of Professional Conduct requires prosecutors to "make timely disclosure to the defense of all evidence or information that tends to negate the guilt of the accused or mitigates the offense." This can result in a mistrial in the latter case and/or the dismissal of the prosecutor.
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. 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.
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.
United States v. Cortez, 449 U.S. 411 (1981), was a United States Supreme Court decision clarifying the reasonable suspicion standard for the investigative stop of a vehicle.
