Which statement about the reasonableness of a formal arrest is correct?

• A. It can be based solely on suspicion
• B. It does not require probable cause if in public
• C. It can be based on a tip
• D. It must be supported by probable cause

Answer: (D)

Probable cause is required for a formal arrest. This means the officer must have facts and trustworthy information that would lead a reasonable person to believe the suspect has committed a crime. The arrest is a significant seizure, and the Fourth Amendment protects against unreasonable invasions, so mere suspicion isn’t enough. A tip can contribute to probable cause only if it is reliable and corroborated by independent facts; by itself, a tip often isn’t sufficient. Even though police can act on suspicions in some contexts (like stops based on reasonable suspicion), a formal arrest hinges on probable cause.