NEW YORK: More than a hundred residents, police officers, scholars and lawmakers are expected to testify about the New York police department's controversial tactic of stopping, questioning and sometimes frisking people on the street.

Police have made about 5 million stops in the past decade of New Yorkers, mostly black and Hispanic men. The trial, set to begin Monday, will include testimony from a dozen people who say they were targeted because of their race.

"We're putting the NYPD on trial, and the stakes are the constitutional rights of hundreds of thousands of New Yorkers," said Vincent Warren, director of the Center for Constitutional Rights, which filed the suit in 2008 on behalf of four men who said they were wrongly stopped.

The case has since become a class-action suit that seeks a court-appointed monitor to oversee changes to how the police make stops. The trial is expected to last more than a month.

Lawyers also plan to play hours of audio tapes made by Adrian Schoolcraft, an officer who was hauled off to a psych ward against his will after he said he refused to fill illegal quotas. His former bosses, including some reassigned after their statements were made public, are also expected.

U.S. District Court Judge Shira Scheindlin, who has already said in earlier rulings that she is deeply concerned about stop and frisk, is not being asked to ban the tactic, since it has been found to be legal. But she does have the power to order reforms, which could bring major changes to how the nation's largest police force and other departments use the tactic.

Street stops have become a New York flashpoint, with mass demonstrations, city council hearings, mayoral candidates calling for reform, and, most recently, days of protests following the fatal police shooting of a teen who authorities say pulled out a gun during a stop.

New York Mayor Michael Bloomberg and Police Commissioner Raymond Kelly say it is a necessary, life-saving, crime-fighting tool that helps keep illegal guns off the street, and has helped New York reach all-time crime lows.

"All of the NYPD's policing practices - including making arrests, conducting investigations, and detaining and questioning people who act suspiciously - are directed at preventing crime and promoting public safety citywide," said city Law Department attorney Celeste Koeleveld.

Street stops increased substantially in the mid-1990s, when, faced with overwhelming crime, then-Mayor Rudy Giuliani made stop-and-frisk an integral part of the city's law enforcement, relying on the "broken windows" theory that targeting low-level offenses helps prevent bigger ones.

Stops rose, and overall crime dropped dramatically in a city that once had the highest murder rate in the U.S.

There were only 419 murders in 2012, the lowest since similar record-keeping began in the 1960s, down from more than 2,000 in the 1990s. And there were 531,159 people stopped, more than five times the number when Bloomberg took office a decade ago. Fifty-one percent of those stopped were black, 32 percent Hispanic and 11 percent white. According to U.S. Census figures, there are 8.2 million people in the city: 26 percent are black, 28 percent are Hispanic and 44 percent are white.

About half of the people are just questioned. Others have their bag or backpack searched. And sometimes police conduct a full pat-down. Only 10 percent of all stops result in arrest, and a weapon is recovered a fraction of the time.