There's a racial bias to marijuana arrests. US Marshals / Shane T. McCoy

People of color accounted for more than nine out of 10 arrests made on suspicion of marijuana possession and sale in New York City from January to March, according to statistics from the New York State Division of Criminal Justice Services obtained by the Police Reform Organizing Project.

PROP also found that 86.5% of New York Police Department misdemeanor arrests involved people of color, up 2% from 2015.

Arrests for "small amounts" of marijuana were up a whopping 33.7% from last year.

Robert Gangi, PROP's director, said in a press release that the statistics showed that NYPD arrest practices are marked by "waste and racial bias" and that, despite the rhetoric in City Hall, marijuana infractions remain a major focus of the police.

"While Mayor de Blasio, NYPD Commissioner Bratton, and other city officials have made widely publicized pronouncements about reducing punitive sanctions for marijuana infractions, the data present a different story," Gangi said. "Arrests for these activities are actually on the rise."

The NYPD was not immediately available for comment.

Steve Zeidman, a law professor at City University of New York and a longtime police-reform advocate, said in an email to Business Insider that the fact that marijuana-related arrests had risen in New York despite changing public opinion — and the fact people of color are overrepresented in the arrest statistics — "should sound very loudly all kinds of alarm bells."

Marijuana possession arrest rates in 2010. ACLU

In 2010, the white arrest rate for marijuana possession nationwide was 192 per 100,000, while the black arrest rate was 716 per 100,000, according to a 2013 ACLU report.

The racial disparity in the arrest rate has increased over the past decade too. While the white arrest rate has stayed constant at 192 per 100,000, the black arrest rate has risen from 537 per 100,000 in 2001 to 716 per 100,000 in 2010.

Rate of marijuana use are more or less identical between whites and blacks, according to data from the National Household Survey on Drug Abuse and Health.

ACLU Zeidman offered some insight into what is behind the disparity.

"Think of it this way," Zeidman said. "Let's say 50 cops are patrolling a Black neighborhood (designated by the NYPD as "high-crime") and 5 cops are patrolling a white neighborhood. In which neighborhood is a teenager smoking a joint more likely to be seen and arrested?"