Reasonable suspicion

Reasonable suspicion or reasonable articulable suspicion is a legal standard of proof that may be required in many jurisdictions, particularly in common law countries. In the United States law it is considered less than probable cause, the legal standard for arrests and warrants, but more than an "inchoate and unparticularized suspicion or 'hunch'"; it must be based on "specific and articulable facts", "taken together with rational inferences from those facts", and the suspicion must be associated with the specific individual.

If law enforcement agents additionally have reasonable suspicion that a person so detained is armed and dangerous, they may "frisk" the person for weapons, but not for contraband like drugs. However, the practice and legality of such actions vary widely across jurisdictions. If the agent develops probable cause during a weapons frisk (for example, by feeling something that could be a weapon or contraband), they may then conduct a full search. Reasonable suspicion is evaluated using the "reasonable person" or "reasonable officer" standard, in which said person in the same circumstances could reasonably suspect a person has been, is, or is about to be engaged in criminal activity; it depends upon the totality of circumstances, and can result from a combination of particular facts, even if each is individually innocuous.