The U.S.Department of Education recently announced it was investigating Fayetteville Public Schools in Arkansas, much to the district's surprise.The reason, according to a department press release: Teachers there "were directed to take students' racial identities into account when issuing discipline as part of an effort to bring about 'restorative justice' to address 'the disproportionality of discipline on students of color.'"Superintendent John Mulford says the district received notice of the investigation roughly two hours before the department publicly named Fayetteville as a target in its national release."We're a little shocked at this point and completely in the dark as to what this is even about," Mulford says.In the same announcement, the department's Office for Civil Rights (OCR) issued new federal guidance warning school leaders that they should not consider a student's race in discipline matters or they would risk being investigated."The hardest part to swallow," Mulford says, is that "ever since I've been here, we've done extensive work around the consistency of our discipline policy… so that it takes away any ambiguity at all." And that, Mulford says, "aligns very well with [federal civil rights law]."That's why, he says, he's "a little taken aback." For now, he's left to wait for clarity from the department.The new guidance and the Fayetteville investigation reopen an old and bitter civil rights fight over discipline in the nation's K-12 schools — and what qualifies as discrimination.Multiple federal investigations have found that discrimination still plagues America's schools, even as it's been illegal for decades, thanks to federal civil rights law.But what if a school policy seems neutral — until you dig into its impact on students? What if data shows that the policy is disproportionately hurting one group? Is that also discrimination?In 2014, the Obama administration issued guidance to the nation's schools arguing that discipline data — s...