The Fourth Amendment to the United States Constitution is part of the Bill of Rights. It prohibits unreasonable searches and seizures and 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.
The open-fields doctrine, in the U.S. law of criminal procedure, is the legal doctrine that a "warrantless search of the area outside a property owner's curtilage" does not violate the Fourth Amendment to the United States Constitution. However, "unless there is some other legal basis for the search," such a search "must exclude the home and any adjoining land that is within an enclosure or otherwise protected from public scrutiny."
In common law, the curtilage of a house or dwelling is the land immediately surrounding it, including any closely associated buildings and structures, but excluding any associated "open fields beyond". In feudal times every castle with its dependent buildings was protected by a surrounding wall, and all the land within the wall was termed the curtilage. The term excludes any closely associated buildings, structures, or divisions that contain the separate intimate activities of their own respective occupants, with those occupying residents being persons other than those residents of the house or dwelling of which the building is associated.
Katz v. United States, 389 U.S. 347 (1967), was a landmark decision of the U.S. Supreme Court in which the Court redefined what constitutes a "search" or "seizure" with regard to the protections of the Fourth Amendment to the U.S. Constitution. The ruling expanded the Fourth Amendment's protections from an individual's "persons, houses, papers, and effects", as specified in the Constitution's text, to include any areas where a person has a "reasonable expectation of privacy". The reasonable expectation of privacy standard, now known as the Katz test, was formulated in a concurring opinion by Justice John Marshall Harlan II.
Florida v. Riley, 488 U.S. 445 (1989), was a United States Supreme Court decision which held that police officials do not need a warrant to observe an individual's property from public airspace.
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.
Kyllo v. United States, 533 U.S. 27 (2001), was a decision by the Supreme Court of the United States in which the court ruled that the use of thermal imaging devices to monitor heat radiation in or around a person's home, even if conducted from a public vantage point, is unconstitutional without a search warrant. In its majority opinion, the court held that thermal imaging constitutes a "search" under the Fourth Amendment, as the police were using devices to "explore details of the home that would previously have been unknowable without physical intrusion." The ruling has been noted for refining the reasonable expectation of privacy doctrine in light of new surveillance technologies, and when those are used in areas that are accessible to the public. This case has been praised by legal scholars since the Court refused to be the arbiter to determine "what is and is not intimate" and thus worthy of protection. Instead, the Court opted to focus on "the invasiveness of the technology itself" and its ability to enable all kinds of government surveillance in the home.
In United States constitutional law, 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 U.S. 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.
Smith v. Maryland, 442 U.S. 735 (1979), was a Supreme Court case holding that the installation and use of a pen register by the police to obtain information on a suspect's telephone calls was not a "search" within the meaning of the Fourth Amendment to the United States Constitution, and hence no search warrant was required. In the majority opinion, Justice Harry Blackmun rejected the idea that the installation and use of a pen register constitutes a violation of the suspect's reasonable expectation of privacy since the telephone numbers would be available to and recorded by the phone company anyway.
United States v. Dunn, 480 U.S. 294 (1987), is a U.S. Supreme Court decision relating to the open fields doctrine limiting the Fourth Amendment of the U.S. Constitution.
Zurcher v. Stanford Daily, 436 U.S. 547 (1978), is a United States Supreme Court case from 1978 in which The Stanford Daily, a student newspaper at Stanford University, was searched by police who had suspected the paper to be in possession of photographs of a demonstration that took place at the university's hospital in April 1971. The Stanford Daily filed a suit claiming that under the protection of the First and Fourth Amendments of the Constitution, the warrants were unconstitutional and that the searches should have fallen under the context of subpoenas. The Supreme Court ruled against The Stanford Daily; however, Congress later passed the Privacy Protection Act of 1980, which provides additional protections against searches and seizures to the press and individuals who disseminate information to the public, unless the individual is suspected of a crime or a life-threatening situation is present.
United States v. White, 401 U.S. 745 (1971), was a United States Supreme Court decision which held that recording conversations using concealed radio transmitters worn by informants does not violate the Fourth Amendment protection against unreasonable searches and seizures, and thus does not require a warrant.
United States v. Knotts, 460 U.S. 276 (1983), was a United States Supreme Court case regarding the use of an electronic surveillance device. The defendants argued that the use of this device was a Fourth Amendment violation. The device in question was described as a beeper that could only be tracked from a short distance. During a single trip, officers followed a car containing the beeper, relying on beeper signal to determine the car's final destination. The Court unanimously held that since the use of such a device did not violate a legitimate expectation of privacy there was no search and seizure and thus the use was allowed without a warrant. It reasoned that a person traveling in public has no expectation of privacy in one's movements. Since there was no search and seizure there was not a Fourth Amendment violation.
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.
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.
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.
Dow Chemical Co. v. United States, 476 U.S. 227 (1986), was a United States Supreme Court case decided in 1986 dealing with the right to privacy and advanced technology of aerial surveillance.
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.
United States v. Miller, 425 U.S. 435 (1976), was a United States Supreme Court that held that bank records are not subject to protection under the Fourth Amendment to the United States Constitution. The case, along with Smith v. Maryland, established the principle of the third-party doctrine in relation to privacy rights.
The aerial surveillance doctrine is the legal doctrine in the United States of America that under the Fourth Amendment, aerial surveillance of an individual’s property does not inherently constitute a search for which law enforcement must obtain a warrant. Courts have used several factors–sometimes only one or a few, other times many or all of them–to determine whether the surveillance in question is a search in violation of one’s constitutional rights: the object of the surveillance, the technology employed, the duration of the surveillance, scope of aggregated information, and the vantage point from which the surveillance is conducted.
