A new report finds black people remain more likely to face pot charges in Colorado, where cops are performing thousands of fewer arrests in keeping with the state's pioneering legalization law.

Legalization advocates generally note unequal enforcement outcomes alongside arguments that regulation can reduce criminality and reap tax windfalls. Colorado and Washington voters took the leap in 2012, followed by Alaska, Oregon and District of Columbia voters in November.

Colorado’s legalization law allows most adults to possess 1 ounce of marijuana, to grow six plants at home and to gift up to an ounce to friends. The law took effect in late 2012 and state-regulated stores opened in January 2014.

The new report, published by the pro-legalization Drug Policy Alliance using law enforcement data, finds pot-related arrests fell roughly 85 percent from 2010 to 2014. But, report author Jon Gettman of Shenandoah University found, “racial disparities for marijuana offenses persist at similar levels."

Excluding data from Denver, the state’s largest city, there were 2,036 pot charges in the first nine months of 2014, the report says. Most – 1,922 – were for possession, 23 were for distribution and 91 for cultivation offenses. Annual pot charges in 2010 and 2011, by comparison, hovered near 40,000.

Despite the steep decline in busts, blacks continued to face higher per capita arrest rates.

The arrest rate for possession, for example, remained about 2.4 times higher for blacks than whites. The gap for distribution arrests narrowed slightly, with blacks going from 6.9 to 5.4 times more likely to be nabbed, while African-Americans went from being less likely to 2.5 times more likely to be charged with cultivation crimes.

In Denver, where pot charges do not neatly align with state law, some types of enforcement spiked, but it's unclear if there were racial disparities.

In the first nine months of 2014, there were 295 actions against people allegedly using the drug in Denver parks – a charge not applied in previous years – and 891 charges for public consumption, up from 184 in all of 2013. City possession charges, however, continued to decline to 351 in the nine-month period, down from 667 in 2013 and 1,548 in 2012.

Though Denver disparities aren't clear, the report finds blacks generally face a higher rate of charges for public consumption, the most common charge in the city.

In El Paso County, which outside Denver led the state in consumption busts, blacks were more than three times more likely to be among the 71 arrested. In next-place Arapahoe and Larimer counties the rates were about two and three times higher from blacks than whites.

Similar racial disparities were seen in Seattle after Washington state legalized marijuana. Of the 82 public consumption tickets written by city cops in the first half of 2014, 37 went to blacks, who make up 8 percent of the city population, and 50 to whites, who make up 70 percent of the population, the Seattle Times reported.

A large national study of 2010 arrest data by the American Civil Liberties Union found blacks were about four times more likely than whites to face marijuana-related charges that year.

The reason for racial enforcement disparities is a matter of debate. Surveys show similar rates of pot use among white and black Americans. Possible explanations include higher rates of poverty among blacks making them more likely to encounter police, or racial bias by law enforcement, or greater rates of residents reporting pot use to police in black-majority neighborhoods.

Whatever the explanation, the continued racial disparity brought unease amid otherwise celebratory news for drug policy reformers.

“The overall decrease in arrests, charges and cases is enormously beneficial to communities of color who bore the brunt of marijuana prohibition prior to the passage of Amendment 64,” said Rosemary Harris Lytle, Regional Chair of the NAACP, in a statement. “However, we are concerned with the rise in disparity for the charge of public consumption and challenge law enforcement to ensure this reality is not discriminatory in any manner.”

Editorial Cartoons on Marijuana View All 15 Images

"Since its inception, the war on drugs has been a war on people of color," says Neill Franklin, a retired Maryland policeman who leads the group Law Enforcement Against Prohibition.

"It's disappointing to see racial disparities still exist even within the limited range of offenses with which police are able to charge people," Franklin says, "but it's a great example why ending the drug war – not just legalizing marijuana – should be one of our top priorities in this country."