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.
Stanley v. Georgia, 394 U.S. 557 (1969), was a United States Supreme Court decision that helped to establish an implied "right to privacy" in U.S. law, in the form of mere possession of obscene materials.
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.
Expectation of privacy is a legal test which is crucial in defining the scope of the applicability of the privacy protections of the Fourth Amendment to the United States Constitution. It is related to, but is not the same as, a right to privacy, a much broader concept which is found in many legal systems. Overall, expectations of privacy can be subjective or objective.
Samson v. California, 547 U.S. 843 (2006), is a United States Supreme Court case in which the Court affirmed the decision of the California Court of Appeal; which held that suspicionless searches of parolees are lawful under California law and that the search in this case was reasonable under the Fourth Amendment to the United States Constitution because it was not arbitrary, capricious, or harassing.
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.
Board of Education v. Earls, 536 U.S. 822 (2002), was a United States Supreme Court case in which the Court upheld the constitutionality of mandatory drug testing by public schools of students participating in extracurricular activities. The legal challenge to the practice was brought by two students, Lindsay Earls and Daniel James, and their families against the school board of Tecumseh, Oklahoma, alleging that their policy requiring students to consent to random urinalysis testing for drug use violated the Fourth Amendment to the United States Constitution.
Vernonia School District 47J v. Acton, 515 U.S. 646 (1995), was a U.S. Supreme Court decision which upheld the constitutionality of random drug testing regimen implemented by the local public schools in Vernonia, Oregon. Under that regimen, student athletes were required to submit to random drug testing before being allowed to participate in sports. During the season, 10% of all athletes were selected at random for testing. The Supreme Court held that although the tests were searches under the Fourth Amendment, they were reasonable in light of the schools' interest in preventing teenage drug use.
National Treasury Employees Union v. Von Raab, 489 U.S. 656 (1989), was a United States Supreme Court case involving the Fourth Amendment and its implication on drug testing programs. The majority of the Court upheld the drug testing program in United States Customs Service.
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.
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.
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.
In Maryland v. King, 569 U.S. 435 (2013), the United States Supreme Court decided 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.
Hudson v. Palmer, 468 U.S. 517 (1984), is a United States Supreme Court case in which the Court held that prison inmates have no privacy rights in their cells protected by the Fourth Amendment to the United States Constitution. The Court also held that an intentional deprivation of property by a state employee "does not violate the Fourteenth Amendment if an adequate postdeprivation state remedy exists," extending Parratt v. Taylor to intentional torts.
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.
