Fourth Amendment: Detention, Arrest, Search & Seizure Complete 70 Question Study Guide 06.04.2026 GV331OPa Unruhest

What is a seizure under the Fourth Amendment?

When a person submits to an officer's show of authority or the officer gains physical control.

Does every police encounter count as a seizure?

No. Only encounters involving restraint of liberty trigger Fourth Amendment protections.

What case defines when a person is seized?

California v. Hodari D. — no seizure until submission or physical restraint.

What makes a seizure unreasonable?

Lack of adequate grounds, failure to obtain a required warrant, or excessive force.

What is a 'show of legal authority'?

Police conduct that signals a person is not free to leave or ignore the officer.

What are the three types of police-citizen interactions?

Voluntary encounters, investigatory (Terry) stops, and arrests.

What makes an encounter voluntary?

No restriction on movement and no indication that compliance is mandatory.

What ends the voluntary nature of an encounter?

A show of legal authority that communicates the person is not free to leave.

What level of suspicion is needed for a voluntary encounter?

None. Officers may approach and ask questions without suspicion.

What level of suspicion is needed for a Terry stop?

Reasonable suspicion that criminal activity may be afoot.

What level of suspicion is needed for an arrest?

Probable cause.

What is reasonable suspicion?

Specific, articulable facts suggesting criminal activity may be occurring.

Can reasonable suspicion be based on a hunch?

No. It must be based on objective facts.

What must officers be able to articulate to justify a Terry stop?

Behavior different from what an innocent person would normally exhibit.

What case supports reasonable suspicion based on flight in a high-crime area?

Illinois v. Wardlow.

Can anonymous tips create reasonable suspicion?

Yes, if sufficiently reliable (Navarette v. California).

What is the purpose of reasonable suspicion?

To allow brief investigation to confirm or dispel suspicion.

What is the purpose of a Terry stop?

To briefly investigate whether criminal activity may be afoot and confirm or dispel suspicion.

What level of suspicion is required for a Terry stop?

Reasonable suspicion based on specific, articulable facts.

What case created the Terry stop doctrine?

Terry v. Ohio (1968).

What is the scope of a Terry stop?

Limited in duration and intrusiveness; only what is necessary to investigate the suspicion.

What actions are prohibited during a Terry stop?

Taking the detainee to the station, searching for evidence (only weapons allowed), moving the detainee unnecessarily, delaying the stop to investigate unrelated matters.

When can an officer frisk during a Terry stop?

When the officer has reasonable suspicion the person is armed and dangerous.

What is the purpose of a frisk?

Officer safety — to locate weapons, not evidence.

What case allows seizure of contraband during a frisk if its identity is immediately apparent?

Plain Feel Doctrine — Minnesota v. Dickerson.

What is the key difference between a stop and an arrest?

The level of intrusion and duration.

When does a Terry stop become a de facto arrest?

When the stop becomes too long or too intrusive to be justified by reasonable suspicion.

What actions can turn a stop into an arrest?

Transporting the suspect, handcuffing without safety justification, drawing weapons unnecessarily, prolonged detention, moving the suspect to a second location.

What level of suspicion is required for an arrest?

Probable cause.

What case discusses when a stop becomes an arrest?

United States v. Place (1983).

What is probable cause?

Facts and circumstances that would lead a reasonable person to believe a crime has been committed and the suspect committed it.

Is probable cause a higher standard than reasonable suspicion?

Yes — it requires more evidence or more reliable evidence.

What sources can establish probable cause?

Officer observations, victim/witness statements, reliable informants, physical evidence, officer training and experience.

Does an officer need to give the correct reason for an arrest?

No. If probable cause exists for any offense, the arrest is valid.

What case requires a post-arrest probable cause determination within 48 hours?

County of Riverside v. McLaughlin (1991).

What level of suspicion is required for a traffic stop?

Either reasonable suspicion of criminal activity or probable cause of a traffic violation.

What case prohibits random stops to check licenses and registration?

Delaware v. Prouse (1978).

What are officers allowed to do during a routine traffic stop?

Order driver and passengers out, ask about weapons, shine flashlight inside, run license, registration, and warrant checks.

When can officers frisk a driver or passenger during a stop?

Only with reasonable suspicion they are armed and dangerous.

Can officers investigate unrelated crimes during a traffic stop?

Yes, as long as it does not prolong the stop.

What case says officers cannot extend a stop for a dog sniff without reasonable suspicion?

Rodriguez v. United States (2015).

What is the only Fourth Amendment requirement for a valid arrest (outside a home)?

Probable cause.

When is an arrest warrant required?

To arrest someone inside their home, absent consent or exigent circumstances.

What is required to arrest someone in a third party's home?

An arrest warrant and a search warrant.

What must an arrest warrant affidavit include?

Probable cause facts, oath or affirmation, particular description of the person.

What is the 'knock and announce' rule?

Officers must announce presence before forced entry unless excused by danger, futility, or destruction of evidence.

What case requires a probable cause hearing within 48 hours after a warrantless arrest?

County of Riverside v. McLaughlin.

What standard governs all police use of force under the Fourth Amendment?

Objective reasonableness.

What case governs deadly force against fleeing suspects?

Tennessee v. Garner (1985).

When is deadly force justified?

When the officer has probable cause the suspect poses a significant threat of death or serious bodily harm.

What case allows high-speed chase force when the suspect endangers the public?

Scott v. Harris.

What case allows officers to fire multiple shots if the threat continues?

Plumhoff v. Rickard.

What is a search under the Fourth Amendment?

Government intrusion into a reasonable expectation of privacy or physical trespass for information.

What case created the reasonable expectation of privacy test?

Katz v. United States.

What case revived the trespass-based definition of a search?

Florida v. Jardines.

What areas are considered curtilage?

Areas immediately surrounding the home, like porches, yards, and driveways.

Are private searches covered by the Fourth Amendment?

No, unless police exceed the scope of the private search.

Is abandoned property protected?

No. No expectation of privacy.

Are canine sniffs of luggage a search?

No, if they do not prolong the stop.

Are canine sniffs at the front door of a home a search?

Yes — Florida v. Jardines.

What are the major exceptions to the warrant requirement?

Consent, search incident to arrest, automobile exception, exigent circumstances, hot pursuit, plain view, inventory searches, Terry frisk (weapons only).

What makes consent valid?

Voluntary, knowing, and given by someone with authority.

What case says officers may not search cell phone data incident to arrest?

Riley v. California.

What are the three requirements for plain view seizure?

Lawful presence, immediately apparent illegality, lawful access to the object.

What case says officers cannot move objects to gain probable cause?

Arizona v. Hicks.

What is the automobile exception?

Officers may search a vehicle with probable cause that it contains evidence or contraband.

What areas may be searched incident to arrest of a vehicle occupant?

Passenger compartment if arrestee is unsecured, areas where evidence of the offense of arrest may be found (Arizona v. Gant).

What is a vehicle weapons sweep?

A limited search of areas where a weapon could be hidden, based on reasonable suspicion.

What is the plain-feel doctrine?

Officers may seize contraband felt during a lawful frisk if its identity is immediately apparent.

During a traffic stop, an officer finishes writing a warning but keeps the driver for a dog sniff without suspicion. Is this lawful?

No. Extending the stop without reasonable suspicion violates Rodriguez v. United States.