Black dentist Elmo Randolph was pulled over by police on the New Jersey turnpike more than fifty times between 1991 and 1999. He was never given a ticket or cited for erratic driving. Instead, Randolph reports, an officer would approach his BMW, request his license and registration, and ask if he had any drugs or weapons in the car. Randolph contends that the only reason he has been stopped so often is because police are suspicious when they see a black man driving an expensive car: “Would they pull over a white middle-class person and ask the same question"”

Many maintain that police officers stereotype minorities as prone to criminal behavior and therefore they disproportionately stop and search blacks and Latinos. Statistics lend support to these charges. According to the New Jersey attorney general, 77 percent of the drivers stopped and searched by...