Police can stop and frisk (pat-down) a suspect based on a reasonable suspicion that the person committed or was about to commit a crime
The right of police to stop and frisk a suspect without having probable cause to do so is called the “Terry Pat-Down” rule.
The Supreme Court in Terry v. Ohio, 392 U.S. 1 (1968) held that law enforcement could legally detain and frisk a suspect without having probable cause to believe a crime was or is in the initial stages of being committed and that the suspect may be armed and dangerous.
The Supreme Court ruled that the standard to stop and frisk should be based on whether the officer had a “reasonable suspicion” to do so – a much lower threshold than probable cause.
The Supreme Court reasoned that officer safety was a primary factor for lowering the standard to reasonable suspicion. The Court held that outside of a “pat-down,” any further search of the suspect by law enforcement required a warrant or sufficient probable cause.