What is the difference between a stop and an arrest under the Fourth Amendment?

• A. An arrest requires probable cause; a stop requires reasonable suspicion.
• B. A stop requires probable cause; an arrest requires reasonable suspicion.
• C. Both require probable cause.
• D. Both require reasonable suspicion.

Answer: (A)

The key idea is the level of justification for different police actions under the Fourth Amendment. A stop (a brief, investigatory detainment) can be justified when the officer has reasonable suspicion that criminal activity is afoot. That means specific, articulable facts that, taken together with the circumstances, would lead a reasonable person to suspect something unlawful is happening. The intrusion is limited and typically short, and a protective frisk for weapons can be allowed if there’s reasonable suspicion the person is armed and dangerous.

An arrest, by contrast, seizes a person and places them in custody and must be supported by probable cause. Probable cause means there are enough facts and circumstances to lead a reasonable person to believe the suspect has committed or is committing a crime. This is a higher standard than reasonable suspicion.

So the difference lies in the level of suspicion required and the resulting restraint: stops require reasonable suspicion, while arrests require probable cause.