In at least one year, the white usage rate was higher. The others, the black usage rate was higher, but in no year were results for the two races that different. For young people ages 18-25, the rates of use are higher for whites:
And more blacks say they've never used marijuana:
Of course, this doesn't translate to roughly equal arrest rates. Not even close:
And this is a uniform phenomenon. It's not that some states treat the races equally and others treat them really unequally. Only in Hawaii are the rates even close to equal, and that's biased by the fact that blacks make up only 1.6 percent of the population. In the state with the second-lowest disparity, Alaska, blacks are 1.6 times more likely to be arrested. In the state with the biggest, Iowa, blacks are 8.34 times more likely to be arrested. D.C. has the second biggest; in the District, blacks are 8.05 times more likely to be arrested.
Similarly, the vast majority of counties arrest blacks at a higher rate than whites, with some having a disparity of greater than 10 to 1:
And this includes a lot of urban areas that are highly populated and liberal-leaning. Cook County, Illinois, which includes Chicago, has one of the largest disparities of any county. So does New York County (Manhattan) and Kings County, N.Y. (Brooklyn):
How important is this? Well, while making up a quite small share of our prison population, marijuana possession charges make up nearly half of total drug arrests:
Obviously, being arrested without going to jail is a lot better than getting arrested and going to jail. But it's still a major nuisance, leading to fines, long hours of community service and thousands of dollars in legal fees.
The report does suggest that legal reforms, in particular decriminalization, is effective at reducing overall arrest rates. Massachusetts decriminalized the possession of small amounts of marijuana in 2009, and arrests dropped an enormous amount:
But interestingly, the racial disparity in arrests did not fall at all:
In 2008, the black arrest rate in Massachusetts was 3.41 times the white arrest rate. In 2009, it was 5.4 times the white arrest rate. Now, the importance of the disparity diminishes when overall arrests are falling that dramatically, and there's no reason to think that decriminalization caused the disparity to increase; in 2010, it fell back down to 3.81.
But it's hard to make the case that decriminalization made enforcement more equitable. Indeed, as Stanford med school Professor Keith Humphreys notes, the states that have legalized or decriminalized marijuana to date all have smaller-than-average black populations. That suggests that whatever benefits casual marijuana users have received from those policies have mainly accrued to white smokers.