Search and Seizure (Fourth Amendment)
The Fourth Amendment protects against unreasonable searches and seizures, requiring warrants supported by probable cause with exceptions for consent, exigent circumstances, and other recognized categories.
Overview
The Fourth Amendment protects individuals from unreasonable searches and seizures by the government, requiring that warrants be supported by probable cause and particularly describe the place to be searched and persons or things to be seized.
The threshold question is whether a "search" occurred. Under Katz v. United States, a search occurs when the government violates a person's reasonable expectation of privacy — requiring both a subjective expectation of privacy and one that society recognizes as reasonable. The Court has applied this framework to find searches in wiretapping (Katz), thermal imaging of homes (Kyllo v. United States), GPS tracking of vehicles (United States v. Jones), and cell phone location data (Carpenter v. United States).
When a search requires a warrant, the warrant must be supported by probable cause and issued by a neutral magistrate. The probable cause standard requires a fair probability that evidence of a crime will be found. Illinois v. Gates adopted a totality-of-the-circumstances test for evaluating informant tips.
Numerous exceptions to the warrant requirement exist: search incident to arrest (Chimel v. California, Riley v. California for cell phones), consent (Schneckloth v. Bustamonte), plain view, automobile exception (California v. Acevedo), exigent circumstances, stop and frisk (Terry v. Ohio), and inventory searches.
The exclusionary rule (Mapp v. Ohio) prohibits the use of evidence obtained through unconstitutional searches, with exceptions for good faith (United States v. Leon), independent source, inevitable discovery (Nix v. Williams), and attenuation.
Key Takeaway
Fourth Amendment analysis: (1) Was there a search/seizure? (2) Was it reasonable — did the government have a warrant, or does an exception apply? (3) If unreasonable, does the exclusionary rule bar the evidence, or does an exception apply?
Exam Tip
Always start by determining whether a 'search' occurred under Katz. If yes, check for a valid warrant. If no warrant, go through the exceptions one by one. Don't forget to analyze the exclusionary rule and its exceptions separately.
Landmark Cases (17)
Frequently Asked Questions
What is the Katz test for a Fourth Amendment search?
A search occurs when the government violates a reasonable expectation of privacy. The two-part test requires: (1) the person exhibited a subjective expectation of privacy, and (2) society recognizes that expectation as objectively reasonable.
What are the main exceptions to the warrant requirement?
Search incident to arrest, consent, automobile exception, plain view, exigent circumstances, Terry stop and frisk, inventory searches, special needs (schools, borders), and hot pursuit.
What is the exclusionary rule?
The exclusionary rule (Mapp v. Ohio) bars the prosecution from using evidence obtained through an unconstitutional search or seizure. It also applies to the 'fruit of the poisonous tree' — derivative evidence. Exceptions include good faith reliance on a warrant, independent source, inevitable discovery, and attenuation.
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