Drug tests do disproportionately impact people of color, but not in the way the ACLU implies. Rather, economist Abigail K. Wozniak finds, drug testing is actually boosting employment for blacks, particularly those who who are relatively unskilled.

How’s that? To put it simply: In the absence of information, it seems that employers are susceptible to making racist assumptions about who uses drugs and who doesn’t. This suppresses black employment. But in places where drug testing is more common, black employment rises, seemingly given a bit of a lift by the opportunity to prove against stereotype that one is not a drug user.

Maxwell Strachan spoke with the study’s author:

[I]n a phone interview with The Huffington Post, Wozniak cautioned against interpreting the study as proof that employers are explicitly discriminating against black applicants.

“The results don’t look like what you would call typical old-school racism,” Wozniak told HuffPost. “The research in the paper suggest that the bias is coming in more subtle ways.”

“Instead of looking really hard at every applicant, they [employers] have these impressions that they go by,” she continued. “Testing gives them a rule of thumb that avoids this bias.”

That “rule of thumb” appears to help. A lot. In fact, Wozniak found pro-testing laws increase the share of low-skilled, black men working in high-testing industries by up to 30 percent and raise their wages by 12 percent compared to anti-testing states.