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.
California v. Greenwood, 486 U.S. 35 (1988), was a case in which the Supreme Court of the United States held that the Fourth Amendment does not prohibit the warrantless search and seizure of garbage left for collection outside the curtilage of a home.
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.
Chimel v. California, 395 U.S. 752 (1969), was a 1969 United States Supreme Court case in which the Court held that police officers arresting a person at home could not search the entire home without a search warrant, but police may search the area within immediate reach of the person without a warrant. The rule on searches incident to a lawful arrest within the home is now known as the Chimel Rule.
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.
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.
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.
Arizona v. Gant, 556 U.S. 332 (2009), was a United States Supreme Court decision holding that the Fourth Amendment to the United States Constitution requires law enforcement officers to demonstrate an actual and continuing threat to their safety posed by an arrestee, or a need to preserve evidence related to the crime of arrest from tampering by the arrestee, in order to justify a warrantless vehicular search incident to arrest conducted after the vehicle's recent occupants have been arrested and secured.
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.
United States v. Johnson, 457 U.S. 537 (1982), was a United States Supreme Court case.
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.
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.
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.
The Supreme Court of the United States handed down eight per curiam opinions during its 2013 term, which began October 7, 2013 and concluded October 5, 2014.
Riley v. California, 573 U.S. 373 (2014), is a landmark United States Supreme Court case in which the court ruled that the warrantless search and seizure of the digital contents of a cell phone during an arrest is unconstitutional under the Fourth Amendment.
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.
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.
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.
