Search and Seizure
4th Amendment to the United States Constitution
What does the Search and Seizure mean?
The Fourth Amendment protects individuals from unreasonable government searches and seizures. It requires that warrants be supported by probable cause, sworn under oath, and specifically describe what is to be searched or seized. This amendment is the foundation of criminal procedure law regarding police conduct.
Source: U.S. Const. amend. 4
Original Text
“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”
Plain-English Explanation
The Fourth Amendment protects individuals from unreasonable government searches and seizures. It requires that warrants be supported by probable cause, sworn under oath, and specifically describe what is to be searched or seized. This amendment is the foundation of criminal procedure law regarding police conduct.
The Supreme Court has developed extensive doctrine around what constitutes a "search" (the Katz reasonable expectation of privacy test), when warrants are required and when exceptions apply (exigent circumstances, search incident to arrest, automobile exception, plain view, consent), and what remedy exists when the Fourth Amendment is violated (the exclusionary rule).
The Fourth Amendment applies to government actors, not private parties. It protects people, not places, and its protections extend to areas where individuals have a reasonable expectation of privacy.
Key Doctrines
Landmark Cases
Katz v. United States
(1967)Established the "reasonable expectation of privacy" test for determining when government surveillance constitutes a search under the Fourth Amendment, overruling the prior trespass-based approach.
Mapp v. Ohio
(1961)Applied the exclusionary rule to state courts through the Fourteenth Amendment, holding that evidence obtained through unconstitutional searches and seizures is inadmissible in state criminal proceedings.
Terry v. Ohio
(1968)Created the stop-and-frisk doctrine, allowing police to briefly detain and pat down individuals based on reasonable suspicion of criminal activity, a lower standard than probable cause.
Carpenter v. United States
(2018)Held that the government's acquisition of historical cell-site location information (CSLI) constitutes a Fourth Amendment search requiring a warrant, extending privacy protections to digital data.
Riley v. California
(2014)Held that police generally must obtain a warrant before searching the digital contents of a cell phone seized during an arrest, recognizing the vast quantity of personal data stored on modern smartphones.
Arizona v. Gant
(2009)Limited the search-incident-to-arrest exception for vehicle searches, holding that police may search a vehicle incident to arrest only if the arrestee is unsecured and within reaching distance or if evidence of the crime of arrest might be found in the vehicle.
Exam Relevance
The Fourth Amendment is one of the most heavily tested areas in both constitutional law and criminal procedure. Master the Katz test, the warrant requirement and all major exceptions (consent, exigent circumstances, search incident to arrest, automobile, plain view, inventory, special needs), the exclusionary rule and its exceptions (good faith, inevitable discovery, independent source, attenuation), and standing requirements.
Modern Applications
- Warrantless surveillance and bulk data collection by intelligence agencies
- Cell phone searches at the border and during traffic stops
- DNA collection from arrestees and genetic genealogy databases
- Drone surveillance by law enforcement over private property
- Geofence warrants and keyword warrants used by police to identify suspects
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