Judge Shira Scheindlin of Federal District Court in New York made the right call when she refused to dismiss a lawsuit against the New York City Police Department, which alleged that officers use race as a basis for stopping and frisking citizens, rather than reasonable suspicion. The trial will provide an important opportunity to evaluate this increasingly troubling program, which resulted in 600,000 people being stopped on the streets last year alone.

The stop-and-frisk tactic is as old as policing itself. But it has been a central law enforcement tool in New York since the 1990’s, when the police adopted the “broken windows” approach, clamping down on minor crime and emphasizing preventive measures against lawbreaking.

New York has experienced a dramatic reduction in crime. But as Judge Scheindlin pointed out, there is no conclusive proof that widespread use of stop-and-frisk itself drove down crime. Crime fell in many cities, including those that did not adopt the approach.

There is no dispute that minorities are disproportionately singled out. Blacks and Hispanics make up a little more than half of the city’s population but about 85 percent of the people stopped. Supporters of the program argue that minority men are disproportionately represented among offenders as well. But analyses dating back more than a decade have shown that it is not so simple.