More than 100 witnesses in New York, including scholars, police and lawmakers are expected to testify at a federal trial about a controversial New York police department practice.
The practice is known as "stop and frisk." The trial begins Monday.
Police say they must have the ability to stop people randomly if there is something suspicious about them.
Critics say that suspicion is too often based on race, targeting young African American and Latino men.
A dozen people who say they were stopped because of their race are scheduled to testify at the trial. The suit against the nation's largest police department is seeking to have a court-appointed monitor oversee changes to the practice.
The New York Civil Liberties Union says in 2012, more than 530,000 people were stopped by the police and 89 percent were "totally innocent."
NYCLU says of those stopped, 55 percent were African American, 32 percent were Latino and 10 percent were white.
New York Mayor Michael Bloomberg and Police Commissioner Raymond Kelly say stop and frisk is a necessary, life-saving, crime-fighting tool that helps keep illegal guns off the street and has helped New York achieve low crime rates.