Fourth Amendment

MBEMax wiki article — paired with the Criminal Procedure question set on mbemax.com.

One-line summary

The Fourth Amendment guarantees freedom from unreasonable government searches and seizures of people, houses, papers, and effects; its core command is a warrant issued on probable cause, with a web of recognized exceptions.

Mnemonic

S-S-S-P-W-E — State action, Search or Seizure, legitimate Privacy/possession interest, Warrant requirement, Exceptions.

Say "Triple-S PWE": if any element is absent, the Fourth Amendment likely isn't violated.

Core doctrine (overview)

For a detailed treatment of searches, see the companion article Search and Seizure. This article focuses on the broader constitutional architecture and standing, seizures of persons, and the warrant framework.

What is a "search" or "seizure"?

• Search — government intrusion into a reasonable expectation of privacy (Katz v. United States, 389 U.S. 347 (1967)) or physical trespass on a constitutionally protected area for purpose of gathering information (United States v. Jones, 565 U.S. 400 (2012)).
• Seizure of person — when, by physical force or show of authority plus submission, a reasonable person would believe she is not free to leave or terminate the encounter (United States v. Mendenhall, 446 U.S. 544 (1980); California v. Hodari D., 499 U.S. 621 (1991)).
• Seizure of property — meaningful interference with possessory interest.

Standing

A defendant can move to suppress only if his own Fourth Amendment rights were violated — i.e., he had a reasonable expectation of privacy in the place searched or possessory interest in the item seized.

• Overnight guests have standing (Minnesota v. Olson); brief commercial visitors generally do not (Minnesota v. Carter).
• Passengers usually lack standing to challenge a vehicle search, but have standing to challenge the stop itself because they are seized with the driver (Brendlin v. California).

The warrant requirement

A warrant is presumptively required, must be issued by a neutral magistrate on probable cause, supported by oath, and particularly describing the place to be searched and things to be seized.

• Probable cause — fair probability that evidence of crime will be found (Illinois v. Gates, 462 U.S. 213 (1983)) or that a person committed a crime.
• Particularity — limits "general warrants." Overbroad warrants invalid.
• Execution — knock-and-announce absent exception (officer safety, evidence destruction, futility). Hudson v. Michigan: exclusionary rule not triggered by knock-and-announce violations.

Exceptions to the warrant requirement

See Search and Seizure for detailed treatment. In brief:

• Exigent circumstances (hot pursuit, evidence destruction, emergency aid).
• Search incident to lawful arrest (Chimel, Gant).
• Automobile exception (probable cause in a mobile vehicle).
• Plain view (lawful vantage, incriminating nature apparent, lawful access).
• Consent (voluntary, by someone with actual or apparent authority).
• Stop and frisk (Terry v. Ohio — reasonable suspicion).
• Administrative / special needs (schools, borders, checkpoints, probationers).
• Inventory searches (routine, pursuant to standard procedure).

Seizures of persons — the stop-arrest spectrum

1. Consensual encounter — no seizure; no Fourth Amendment analysis.
2. Investigative stop (Terry) — reasonable suspicion; limited duration and scope.
3. Arrest — probable cause; no warrant required for public-place arrests (United States v. Watson), but warrant required for routine in-home arrests absent exigent circumstances (Payton v. New York).

Exclusionary rule and its limits

The judicially crafted remedy is suppression of unlawfully obtained evidence and its "fruits." Exceptions:

• Good-faith reliance on warrant (United States v. Leon) — unless warrant is so lacking in probable cause as to render belief unreasonable, or is facially deficient.
• Inevitable discovery — evidence would have been lawfully discovered anyway (Nix v. Williams).
• Independent source — evidence obtained from a source genuinely independent of the illegality.
• Attenuation of taint — intervening circumstances dilute the connection (Wong Sun, Brown v. Illinois, Utah v. Strieff).
• Knock-and-announce violations do NOT trigger exclusion (Hudson).
• Civil proceedings and grand-jury proceedings — exclusionary rule generally does not apply.

NCBE loves to test

• Katz vs. Jones duality. Either framework can trigger a search — reasonable expectation OR trespass to constitutionally protected area.
• Digital privacy. Riley (cellphones), Carpenter (CSLI), Jones (GPS).
• Consent — apparent authority. Third party with apparent authority can consent; actual authority unnecessary if officer's belief is objectively reasonable (Illinois v. Rodriguez).
• Automobile exception — scope. PC as to whole vehicle allows search of anywhere contraband could be, including passenger containers.
• Seizure of person. Mere police questioning is not a seizure. Pursuit without submission is not a seizure until defendant yields.
• Standing. Overnight guests yes; passengers yes (for the stop) but no (for the vehicle-search). Employees of a business — case-specific.

Fast hypos

Hypo 1. Officers receive an anonymous tip that D is carrying a gun. They confront D at a bus station, ask questions. D cooperates. Consensual encounter — not a seizure.

Hypo 2. Officers with PC stop a car, then search the glove compartment and passenger's purse. Passenger may challenge; automobile exception covers containers where PC reasonably extends.

Hypo 3. Officers execute an arrest warrant at D's home. D answers, is arrested at door, handcuffed, and taken to patrol car. Proper under *Payton if warrant-based, but no additional search-incident to arrest of the house without further justification.*

Hypo 4. Officer with a valid search warrant enters. While searching, officer sees evidence of an unrelated crime in plain view. Seizable under plain-view doctrine if incriminating nature is immediately apparent and officer is lawfully present.

Case anchors

• Katz v. United States, 389 U.S. 347 (1967).
• Terry v. Ohio, 392 U.S. 1 (1968).
• Illinois v. Gates, 462 U.S. 213 (1983).
• Payton v. New York, 445 U.S. 573 (1980).
• United States v. Leon, 468 U.S. 897 (1984).
• Mapp v. Ohio, 367 U.S. 643 (1961).
• Carpenter v. United States, 585 U.S. 296 (2018).
• Riley v. California, 573 U.S. 373 (2014).
• Utah v. Strieff, 579 U.S. 232 (2016) — attenuation after an outstanding warrant discovered during an illegal stop.

See also

• Search and Seizure
• Miranda
• Exclusionary rule

Sources

U.S. Const. amend. IV; Katz v. United States, 389 U.S. 347 (1967); Terry v. Ohio, 392 U.S. 1 (1968); Illinois v. Gates, 462 U.S. 213 (1983); Payton v. New York, 445 U.S. 573 (1980); United States v. Leon, 468 U.S. 897 (1984); Mapp v. Ohio, 367 U.S. 643 (1961); Carpenter v. United States, 585 U.S. 296 (2018); Riley v. California, 573 U.S. 373 (2014); Utah v. Strieff, 579 U.S. 232 (2016).