In criminal procedure law of the United States, an exigent circumstance allows law enforcement to enter a structure without a search warrant, or if they have a "knock and announce" warrant, allows them to enter without knocking and waiting for the owner's permission to enter. It must be a situation where people are in imminent danger, evidence faces imminent destruction, or a suspect's escape is imminent. Once entry is obtained, the plain view doctrine applies, allowing the seizure of any evidence or contraband discovered in the course of actions consequent upon the exigent circumstances.
Georgia v. Randolph, 547 U.S. 103 (2006), is a case in which the U.S. Supreme Court held that without a search warrant, police had no constitutional right to search a house where one resident consents to the search while another resident objects. The Court distinguished this case from the "co-occupant consent rule" established in United States v. Matlock, 415 U.S. 164 (1974), which permitted one resident to consent in absence of the co-occupant.
Brigham City v. Stuart, 547 U.S. 398 (2006), is a United States Supreme Court case involving the exigent circumstances exception to the Fourth Amendment's warrant requirement. The Court ruled that police may enter a home without a warrant if they have an objectively reasonable basis for believing that an occupant is or is about to be seriously injured.
Search incident to a lawful arrest, commonly known as search incident to arrest (SITA) or the Chimel rule, is a U.S. legal principle that allows police to perform a warrantless search of an arrested person, and the area within the arrestee’s immediate control, in the interest of officer safety, the prevention of escape, and the preservation of evidence.
Welsh v. Wisconsin, 466 U.S. 740 (1984), was a 1983 case before the US Supreme Court determining that a warrantless arrest violates the Fourth Amendment protection against unlawful search and seizure.
Implied consent is consent which is not expressly granted by a person, but rather implicitly granted by a person's actions and the facts and circumstances of a particular situation. For example, if a person is unconscious as a result of injuries sustained during a traffic collision, medical treatment may be provided to that person, despite the unconscious person being unable to expressly grant consent for that treatment.
Schmerber v. California, 384 U.S. 757 (1966), was a landmark United States Supreme Court case in which the Court clarified the application of the Fourth Amendment's protection against warrantless searches and the Fifth Amendment right against self-incrimination for searches that intrude into the human body. Until Schmerber, the Supreme Court had not yet clarified whether state police officers must procure a search warrant before taking blood samples from criminal suspects. Likewise, the Court had not yet clarified whether blood evidence taken against the wishes of a criminal suspect may be used against that suspect in the course of a criminal prosecution.
Kentucky v. King, 563 U.S. 452 (2011), was a decision by the US Supreme Court, which held that warrantless searches conducted in police-created exigent circumstances do not violate the Fourth Amendment as long as the police did not create the exigency by violating or threatening to violate the Fourth Amendment.
United States v. Jones, 565 U.S. 400 (2012), was a landmark United States Supreme Court case in which the court held that installing a Global Positioning System (GPS) tracking device on a vehicle and using the device to monitor the vehicle's movements constitutes a search under the Fourth Amendment.
County of Riverside v. McLaughlin, 500 U.S. 44 (1991), was a United States Supreme Court case which involved the question of within what period of time must a suspect arrested without a warrant be brought into court to determine if there is probable cause for holding the suspect in custody. The majority held that suspects must generally be granted a probable cause determination within 48 hours of arrest. The dissent believed that probable cause hearings should generally be provided much sooner, as soon as the police complete the administrative steps incident to arrest.
Missouri v. McNeely, 569 U.S. 141 (2013), was a case decided by United States Supreme Court, on appeal from the Supreme Court of Missouri, regarding exceptions to the Fourth Amendment to the United States Constitution under exigent circumstances. The United States Supreme Court ruled that police must generally obtain a warrant before subjecting a drunken-driving suspect to a blood test, and that the natural metabolism of blood alcohol does not establish a per se exigency that would justify a blood draw without consent.
United States v. Watson, 423 U.S. 411 (1976), was a case decided by the Supreme Court of the United States that decided that a warrantless arrest in public and consenting to a vehicle search did not violate the Fourth Amendment.
Breithaupt v. Abram, 352 U.S. 432 (1957), was a United States Supreme Court case in which the Court ruled that involuntary blood samples, taken by a skilled technician to determine intoxication, do not violate substantive due process under the Fourteenth Amendment of the United States Constitution. This case was only the second time the Court considered whether police could forcibly enter inside a suspect's body to extract evidence. Writing for a 6–3 majority, Justice Tom C. Clark argued that blood tests were necessary as a matter of public policy to ensure traffic safety on roads and highways, and that "modern community living requires modern scientific methods of crime detection." Chief Justice Earl Warren and Justice William O. Douglas both wrote dissenting opinions in which they argued that the involuntary blood sample taken in this case was "repulsive" and violated substantive due process.
South Dakota v. Neville, 459 U.S. 553 (1983), was a United States Supreme Court case in which the Court held that prosecutors may use a suspect's refusal to submit to a blood-alcohol test as evidence of guilt and that the introduction of such evidence at trial does not violate the suspect's Fifth Amendment privilege against self incrimination.
United States v. Drayton, 536 U.S. 194 (2002), was a case in which the United States Supreme Court clarified the applicability of Fourth Amendment protections to searches and seizures that occur on buses, as well as the function of consent during searches by law enforcement. During a scheduled stop in Tallahassee, Florida, police officers boarded a Greyhound bus as part of a drug interdiction effort and interviewed passengers. After talking to two of the passengers and asking if they could "check [their] person", officers discovered the two passengers had taped several packages of cocaine to their legs. At trial, the passengers argued that officers violated their Fourth Amendment rights against unreasonable searches and seizures because the police engaged in coercive behavior and never informed them that their participation in the drug interdiction efforts was voluntary.
Birchfield v. North Dakota, 579 U.S. ___ (2016) is a case in which the Supreme Court of the United States held that the search incident to arrest doctrine permits law enforcement to conduct warrantless breath tests but not blood tests on suspected drunk drivers.
Collins v. Virginia, No. 16-1027, 584 U.S. ___ (2018), was a case before the US Supreme Court involving search and seizure. At issue was whether the Fourth Amendment's motor vehicle exception permits a police officer uninvited and without a warrant to enter private property, approach a house, and search a vehicle parked a few feet from the house that is otherwise visible from off the property. In an 8–1 judgement, the Supreme Court ruled that the automobile exception does not apply to vehicles parked within the home or the curtilage of a private homeowner.
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."
Caniglia v. Strom, 593 U.S. ___ (2021), was a United States Supreme Court case related to the Fourth Amendment to the United States Constitution's "community caretaking" exception.
Lange v. California, 594 U.S. ___ (2021), was a United States Supreme Court case involving the exigent circumstances requirement related to the Fourth Amendment to the United States Constitution. The Court ruled unanimously that the warrantless entry into a home by police in pursuit of a misdemeanant is not unequivocally justified.
