Even as the first residents trickle into city-sanctioned dispensaries for medical marijuana, Washington, D.C., is arresting more people than ever for marijuana possession, says an American Civil Liberties Union study reported by the Washington Post. Possession arrests surged more than 60 percent between 2001 and 2010, one of the largest increases in the U.S. Arrests of African Americans accounted for much of the rise, raising concerns among community leaders and criminal justice experts about racial profiling by police. Of those arrested for possession in Washington, nine out of 10 were African American, a statistic matched only by Baltimore. By contrast, 82 percent of those arrested in Philadelphia were black, and in Brooklyn, 62.5 percent were black. Peter Reuter, a public-policy professor at the University of Maryland who has studied arrest rates for marijuana possession, said age also plays a factor. “If you are a marijuana user under the age of 21, you have a much higher chance of getting arrested than a 35-year-old,” he said. “The real puzzle is why is this going on. If you look at statements by police chiefs across the country, you don't see a crackdown on marijuana. It seems to be the result of other kinds of arrest strategies.” D.C. Police Chief Cathy Lanier denied that the city has made a concerted effort to target marijuana possession.