In what scenario is a "stop and frisk" legally permissible?

A "stop and frisk" is legally permissible under specific circumstances. The scenario where a suspect is acting suspiciously provides law enforcement officers with reasonable suspicion to believe that criminal activity may be afoot. This standard is rooted in the legal precedent established by the Supreme Court in Terry v. Ohio, which allows an officer to stop an individual and perform a limited pat-down of their outer clothing for weapons if the officer has a reasonable belief that the person may be armed and dangerous.

The concept of reasonable suspicion is based on the totality of the circumstances, such as the behavior of the individual, the location, and the time of day. An officer noticing someone acting suspiciously can constitute this reasonable suspicion, thus justifying the "stop and frisk" procedure.

In contrast, a routine check lacks the individualized suspicion required for a stop. Feeling threatened by bystanders may not meet the threshold of reasonable suspicion related to a specific individual. Lastly, a situation with no evidence offers no justification for the necessary suspicion to conduct a stop and frisk. Therefore, when a suspect is acting suspiciously, it aligns with legal standards allowing law enforcement to engage in "stop and frisk" actions.