"Stop-question-and-frisk" (SQF), a form of proactive policing where officers detain and search persons suspected of illegal activity, has been used by police departments for decades. SQF searches are intended to maintain a level of officer vigilance targeting low-level criminal offenses in order to prevent greater, primarily firearm-related offenses. The constitutionality of stop and frisk searches did not come into question until the 1968 US Supreme Court case of Terry v. Ohio, when the Court ruled that the searches did not violate Fourth Amendment rights. "Terry searches," as they came to be known, were found to be permissible when based on "specific and articulable facts," and not simply an officer's hunch.
Terry failed to settle the debate, however, and the constitutionality of stop and frisk searches has been under constant scrutiny. New York City's "Stop-Question-and-Frisk" policy, enacted by Mayor David Dinkins in the 1990s, has been the source of contention since. The searches themselves require officers to reasonably suspect "that a person has committed, is committing or is about to commit a felony or Penal Law misdemeanor," before the officer is permitted to "stop, question and possibly frisk" the individual. The frequency of SQF searches drastically increased under Mayor Rudy Giuliani's administration in the mid-1990s, and the city saw a decrease in its crime rate.
The New York Police Department has stated that its SQF policy has been a significant deterrent of crime, but the New York Civil Liberties Union (NYCLU) and other opponents of the policy see the reported under-20% rate of yielding convictions as indicating that its effects do not outweigh its infringement upon individual privacy. The policy's opponents maintain that SQF searches are in violation of citizens' Fourth Amendment protections from unreasonable searches and seizures. SQF policies are also frequently alleged to unfairly discriminate against low income populations and people of color. In 2011, for example, almost 87 percent of SQF stops involved black and Latino suspects, which is only slightly above the program's average rate.