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.
A search warrant is a court order that a magistrate or judge issues to authorize law enforcement officers to conduct a search of a person, location, or vehicle for evidence of a crime and to confiscate any evidence they find. In most countries, a search warrant cannot be issued in aid of civil process.
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. There is no universally accepted definition or formulation for probable cause. One traditional definition, which comes from the U.S. Supreme Court's 1964 decision Beck v. Ohio, is when "whether at [the moment of arrest] the facts and circumstances within [an officer's] knowledge and of which they had reasonably trustworthy information [are] sufficient to warrant a prudent [person] in believing that [a suspect] had committed or was committing an offense."
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.
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."
Knock-and-announce, in United States law criminal procedure, is an ancient common law principle, incorporated into the Fourth Amendment, which requires law enforcement officers to announce their presence and provide residents with an opportunity to open the door prior to a search.
Maryland v. Garrison, 480 U.S. 79 (1987), is a United States Supreme Court case dealing with the Fourth Amendment of the United States Constitution and the extent of discretion given to police officers acting in good faith. The Court held that where police reasonably believe their warrant was valid during a search, execution of the warrant does not violate respondent's Fourth Amendment rights.
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.
Almeida-Sanchez v. United States, 413 U.S. 266 (1973), was a United States Supreme Court case holding that the 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.
In the law of the United States, the mere evidence rule was a historical doctrine that defined the scope of the Fourth Amendment to the United States Constitution.
Marcus v. Search Warrant, 367 U.S. 717 (1961), full title Marcus v. Search Warrant of Property at 104 East Tenth Street, Kansas City, Missouri, is an in rem case decided by the United States Supreme Court on the seizure of obscene materials. The Court unanimously overturned a Missouri Supreme Court decision upholding the forfeiture of hundreds of magazines confiscated from a Kansas City wholesaler. It held that both Missouri's procedures for the seizure of allegedly obscene material and the execution of the warrant itself violated the Fourth and Fourteenth amendments' prohibitions on search and seizure without due process. Those violations, in turn, threatened the rights protected by the First Amendment.
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.
Soldal v. Cook County, 506 U.S. 56 (1992), was a United States Supreme Court case in which the Court held that a seizure of property like that which occurs during an eviction, even absent a search or an arrest, implicates the Fourth Amendment. The Court also held that the Amendment protects property as well as privacy interests, in both criminal as well as civil contexts. Finally, saying that "certain wrongs affect more than a single right", the Court left open the possibility that the Fourteenth Amendment's protections against deprivation of property without due process of law may also be implicated.
Maryland v. King, 569 U.S. 435 (2013), was a decision of the United States Supreme Court which held that a cheek swab of an arrestee's DNA is comparable to fingerprinting and therefore, a legal police booking procedure that is reasonable under the Fourth Amendment.
Camara v. Municipal Court, 387 U.S. 523 (1967), is a United States Supreme Court case that overruled a previous case and established the ability of a resident to deny entry to a building inspector without a warrant.
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.
The "special needs" exception is an exception to the Fourth Amendment’s general requirement that government searches be supported by a warrant and probable cause. The exception applies when (1) the government conducts programmatic searches that are primarily aimed at advancing some special need other than criminal law enforcement, and (2) the government’s search program is reasonable given the balance of public and private interests.
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."
