Although a federal judge ruled the NYPD's practice of stop and frisk to be unconstitutional, the tactic remains legal if it follows already-established constitutional guidelines. Under the Fourth Amendment, which guards against unreasonable searches and seizures, law enforcement personnel needed 鈥減robable cause鈥� to stop and search someone. That is, they need good reason to believe a person has committed or is about to commit a crime.
But a 1968 US Supreme Court decision, Terry v. Ohio, lowered that benchmark by allowing law enforcement to stop and search people in a public place if the officer 鈥渞easonably suspects鈥� that someone is about to commit a crime, and can "articulate" a valid reason for the stop and frisk. Reasonable suspicion alone is not grounds for arrest, as probable cause is, but incriminating evidence found during a stop and frisk may be grounds for arrest.
The problem is that 鈥渞easonable suspicion鈥� is more vague than 鈥減robable cause,鈥� leading some opponents to argue that law enforcement officers use a person's race to determine reasonable suspicion, and therefore, perform stop and frisks.
