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.
New Jersey v. T.L.O., 469 U.S. 325 (1985), is a case in which the Supreme Court of the United States established the standard of reasonableness for searches of students conducted by public school officials in a school environment. The Court held that the Fourth Amendment to the U.S. Constitution, specifically its prohibition on unreasonable searches and seizures, applies to searches conducted by school officials. However, school officials do not need to have probable cause or obtain a warrant before searching a student. Instead, in order for a search to be justified, school officials must have reasonable suspicion that the student has violated either the law or school rules.
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.
United States v. Ross, 456 U.S. 798 (1982), was a search and seizure case argued before the Supreme Court of the United States. The high court was asked to decide if a legal warrantless search of an automobile allows closed containers found in the vehicle to be searched as well. The appeals court had previously ruled that opening and searching the closed portable containers without a warrant was a violation of the Fourth Amendment, even though the warrantless vehicle search was permissible due to existing precedent.
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.
The motor vehicle exception is a legal rule in the United States that modifies the normal probable cause requirement of the Fourth Amendment to the United States Constitution and, when applicable, allows a police officer to search a motor vehicle without a search warrant.
Ker v. California, 374 U.S. 23 (1963), was a case before the United States Supreme Court, which incorporated the Fourth Amendment's protections against illegal search and seizure. The case was decided on June 10, 1963, by a vote of 5–4.
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.
Wilson v. Arkansas, 514 U.S. 927 (1995), is a United States Supreme Court decision in which the Court held that the traditional, common-law-derived "knock and announce" rule for executing search warrants must be incorporated into the "reasonableness" analysis of whether the actual execution of the warrant is/was justified under the 4th Amendment. The high court thus ruled that the old "knock and announce" rule while not a hard requirement, was also not a dead letter.
Wyoming v. Houghton, 526 U.S. 295 (1999), is a United States Supreme Court case which held that absent exigency, the warrantless search of a passenger's container capable of holding the object of a search for which there is probable cause is not a violation of the Fourth Amendment to the United States Constitution, because it is justified under the automobile exception as an effect of the car.
Torres v. Puerto Rico, 442 U.S. 465 (1979), was a United States Supreme Court case holding that the Fourth Amendment guarantee against unreasonable search and seizure applies to Puerto Rico.
Chambers v. Maroney, 399 U.S. 42 (1970), was a United States Supreme Court case in which the Court applied the Carroll doctrine in a case with a significant factual difference—the search took place after the vehicle was moved to the stationhouse. The search was thus delayed and did not take place on the highway as in Carroll. After a gas station robbery, a vehicle fitting the description of the robbers' car was stopped. Inside were people wearing clothing matching the description of that worn by the robbers. They were arrested, and the car was taken to the police station where it was later searched.
Brinegar v. United States, 338 U.S. 160 (1949), was a United States Supreme Court case employing the "reasonableness test" in warrantless searches. The Court held that while the police need not always be factually correct in conducting a warrantless search, such a search must always be reasonable.
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."
Florida v. Jardines, 569 U.S. 1 (2013), was a United States Supreme Court case which resulted in the decision that police use of a trained detection dog to sniff for narcotics on the front porch of a private home is a "search" within the meaning of the Fourth Amendment to the United States Constitution, and therefore, without consent, requires both probable cause and a search warrant.
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.
Johnson v. United States, 333 U.S. 10 (1948), was a significant United States Supreme Court decision addressing search warrants and the Fourth Amendment. In this case, where federal agents had probable cause to search a hotel room but did not obtain a warrant, the Court declared the search was "unreasonable."
