While police crack down on drug deals in mostly minority neighborhoods, the drug trade among whites in New York City operates with relative impunity, statistics show. This racial disparity has troubled drug-policy reformers for at least a decade, but recent public scrutiny of the city’s policing policies has made the disparity even more glaring.

In 2009, only 10 percent of the 46,000 people arrested on marijuana-related charges by the New York City Police Department were white, according to a 2010 study — though whites are often among its heaviest drug users.

Likewise, a class-action lawsuit filed against the NYPD in 2008 by the Center for Constitutional Rights, a New York-based nonprofit organization, claims that the city’s stop-and-frisk policy violates the rights of innocent citizens and often amounts to racial profiling.

That racial profiling contributes to disparities in marijuana related arrests, says Harry Levine, a sociology professor at Queens College who has conducted extensive research on New York City drug policy. “Marijuana possession arrests have systematically excluded the largest groups of marijuana users in New York City — whites and the middle class,” said Levine. “Instead, these hundreds of thousands of manufactured marijuana arrests and jailings have fallen overwhelmingly on people least able to defend themselves against the onslaught — young, low-income blacks and Latinos.”

Mayor Bloomberg’s office did not respond to questions regarding the city’s drug enforcement policy or the city’s policing strategies. The NYPD also did not respond to requests seeking comment on the racial disparity of marijuana arrests.