First let’s ask what does Stop and frisk actually mean legally? “It’s the situation in which a police officer who is suspicious of an individual detains the person and runs his hands lightly over the suspect's outer garments to determine if the person is carrying a concealed weapon.”
When and where did this derive from? Well In 1968 the Supreme Court addressed the issue in terry v. Ohio, 392. In Terry an experienced plainclothes officer observed three men acting suspiciously; they were walking back and forth on a street and peering into a particular store window. The officer concluded that the men were preparing to rob a nearby store and approached them. Identifying himself as a police officer he asked for their names bust was unsatisfied with their responses, he then subjected one of the men to a frisk, which produced a gun where as the man had no permit for. In this case the officer did not have a warrant nor did he have probable cause. The defendants argued the search was unreasonable under the Fourth Amendment because it was not supported by probable cause.
The Supreme Court rejected the defendants' arguments. The Court noted that stops and frisks are considerably less intrusive than full-blown arrests and searches. It also observed that the interests in crime prevention and in police safety require that the police have some leeway to act before full probable cause has developed. The Fourth Amendment's reasonableness requirement is sufficiently flexible to permit an officer to investigate the situation. The "sole justification" for a frisk, said the Court, is the "protection of the police officer and others nearby." Because of this narrow scope, a frisk must be "reasonably designed to discover guns,