Cleveland detective McFadden was an officer with 39 years of experience. One October afternoon, he observed two individuals walking back and forth 24 times, pausing briefly to look in a shop window. Based on his experience, McFadden became suspicious. He testified that after observing their elaborately casual and oft-repeated reconnaissance of the shop window, he suspected the two men of “casing a job—a stick-up.” He approached the men and when they mumbled something in response to his inquiry, McFadden frisked Terry, one of the men, and found a .38-caliber revolver. Charged with possession of a concealed weapon, Terry sought to suppress the gun.
As we have seen thus far in the Fourth Amendment context, the justification for an arrest and most criminal searches is probable cause. With regard to an arrest, the police need probable cause that a particular individual has committed a crime. Thus McFadden, who had only observed suspicious activity, did not have probable cause to arrest Terry. The Supreme Court grappled with McFadden's activity in Terry v. Ohio (1968), considering whether actions by the police are appropriate even though no crime has yet occurred. The Court first determined that the Fourth Amendment should apply to such activity. In a decision by Justice Earl Warren, the Court recognized the conflicting tension between the importance of law enforcement intervention in preventing crimes and the protections afforded to an individual by the Fourth Amendment. The Court turned to the reasonableness clause of the Fourth Amendment to create a method to deal with “street encounters between citizens and police officers.” Through the use of the reasonableness clause, the Court weighed the government interest in conducting investigations in the absence of specific crimes against the amount of intrusion such encounters would entail. The Court's solution reflects an attempt to balance the intrusion