Justin Serrano was 13 the first time he was stopped by police. He says he was walking his 7-year-old brother home from school when officers forced him against a wall, patted him down and kept him in the back of a patrol car for more than an hour while both boys cried. Then they let Serrano go, telling him it was a case of mistaken identity.

It was a pivotal moment in Serrano's life. Five years later, he sat with other Hispanic and black teenagers with similar stories at Make the Road, a community organization in Brooklyn's Bushwick section. Guided by two university professors, the teenagers were contributing questions for a survey on the New York City Police Department's "stop-and-frisk" tactic.

The NYPD's policy of detaining and sometimes searching anyone officers deem suspicious has prompted an emotional debate and a federal lawsuit. Opponents argue the strategy is unconstitutional and encourages racial profiling, while the city and its supporters say the stops have contributed to a dramatic drop in violent crime.

The NYPD stopped close to 700,000 people on the street last year, up from more than 90,000 a decade ago. Nearly 87 percent were black or Hispanic. About half were frisked. About 10 percent were arrested.

advertisement | advertise on newsday

A federal judge in May granted class-action status to the lawsuit, meaning thousands of people who have been stopped over the years could potentially join the complaint introduced by the Center for Constitutional Rights on behalf of four black men.

U.S. District Judge Shira Scheindlin said there was "overwhelming evidence" police have conducted thousands of unlawful stops based on flimsy justification such as "furtive movement." But the commissioner and Mayor Michael Bloomberg fiercely defend aggressive policing they credit for transforming New York into one of the safest big cities in the United