Memo to Mayor Bloomberg: a new ACLU report uncovers “staggering racial bias” in the enforcement of marijuana laws. Minorities are arrested at four times the rate of whites, and in some states, eight times higher, despite equal consumption of the drug. Mike Riggs focuses in on the report’s findings in rural areas:

It’s no secret that in big cities like D.C. and New York blacks are arrested for pot far more often than whites, despite comparable usage rates. But the ACLU is the first group to extrapolate arrest numbers across the country. … [In Morgan County, AL] blacks make up 12 percent of the population and 100 percent of the marijuana arrests.

Here’s the NYT map of the new racial profiling:

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More here. Keith Humphreys points to the relative “whiteness” of regions that have loosened marijuana laws to explain why the racial disparity in arrests has worsened over the 10-year period examined in the study:

Why has the softening of marijuana enforcement in the past few years apparently not reduced the African-American arrest rate? The answer may lie in political economy. Until recently, support for legalizing/decriminalizing marijuana has been much higher among Whites among Blacks, which may help account for why enforcement softening spread where it did in the U.S. … [The disproportionately white populations in areas with legalization is] a marked pattern that has thus far meant that White marijuana users are being affected by softening enforcement more than are Black marijuana users. However, some cities with predominantly Black populations (e.g., St. Louis) have recently moved in the decriminalization direction, which may reduce the arrest rate among African-Americans in the coming years.

But not if Mayor Bloomberg has anything to do with it.