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.
Weeks v. United States, 232 U.S. 383 (1914), was a United States Supreme Court case in which the Court unanimously held that the warrantless seizure of items from a private residence constitutes a violation of the Fourth Amendment. It also prevented local officers from securing evidence by means prohibited under the federal exclusionary rule and giving it to their federal colleagues. It was not until the case of Mapp v. Ohio, 367 U.S. 643 (1961), that the exclusionary rule was deemed to apply to state courts as well.
United States v. Place, 462 U.S. 696 (1983), was a decision by the Supreme Court of the United States which held that a sniff of luggage in a public place, by a police dog specially trained to detect the odor of narcotics, was not a "search" under the meaning of the Fourth Amendment to the United States Constitution. The Court reasoned that the sniff of a dog is sui generis, intended to disclose only the presence or absence of narcotics. Because a dog sniff is such a limited test, the Court carved out this exception from the broad category of "searches" for which a warrant is generally required.
Mobile phone tracking is a process for identifying the location of a mobile phone, whether stationary or moving. Localization may be affected by a number of technologies, such as using multilateration of radio signals between (several) cell towers of the network and the phone, or simply using GPS. To locate a mobile phone using multilateration of radio signals, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not require an active call. The Global System for Mobile Communications (GSM) is based on the phone's signal strength to nearby antenna masts.
Olmstead v. United States, 277 U.S. 438 (1928), was a decision of the Supreme Court of the United States, in which the Court reviewed whether the use of wiretapped private telephone conversations, obtained by federal agents without judicial approval and subsequently used as evidence, constituted a violation of the defendant’s rights provided by the Fourth and Fifth Amendments. In a 5-4 decision, the Court held that neither the Fourth Amendment nor the Fifth Amendment rights of the defendant were violated. This decision was later overturned by Katz v. United States in 1967.
United States v. Leon, 468 U.S. 897 (1984), was a United States Supreme Court case in which the Court established the "good faith" exception to the Fourth Amendment exclusionary rule.
Arizona v. Evans, 514 U.S. 1 (1995), was a United States Supreme Court case in which the Court instituted an exclusionary rule exception allowing evidence obtained through a warrantless search to be valid when a police record erroneously indicates the existence of an outstanding warrant due to negligent conduct of a Clerk of Court.
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.
Brendlin v. California, 551 U.S. 249 (2007), was a decision by the Supreme Court of the United States that held that all occupants of a car are "seized" for purposes of the Fourth Amendment during a traffic stop, not just the driver.
Herring v. United States, 555 U.S. 135 (2009), was a case decided by the Supreme Court of the United States on January 14, 2009. The court decided that the good-faith exception to the exclusionary rule applies when a police officer makes an arrest based on an outstanding warrant in another jurisdiction, but the information regarding that warrant is later found to be incorrect because of a negligent error by that agency.
Wilson v. Arkansas, 514 U.S. 927 (1995), is a United States Supreme Court decision in which the Court held that police officers must "knock and announce" before entering a house to serve a warrant.
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.
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 which 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.
Immigration and Naturalization Service v. Delgado, 466 U.S. 210 (1984), was a United States Supreme Court decision finding that a police demand of an individual to identify himself would convert a consensual stop to a Terry stop, whereas a mere request would not.
Pennsylvania v. Mimms, 434 U.S. 106 (1977), is a United States Supreme Court criminal law decision holding that a police officer ordering a person out of a car following a traffic stop and conducting a pat-down to check for weapons did not violate the Fourth Amendment to the United States Constitution.
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 unanimously held that the warrantless search and seizure of digital contents of a cell phone during an arrest is unconstitutional.
