My colleague Andrew Coulson:
Over the past several years, University of Rochester professor Joshua Kinsler has explored this question [of racial disparity in school discipline] using uniquely rich datasets. What he finds is that the variation in punishment between the races is largely explained by variation in discipline policies at the school level: black students are more likely to attend very strict schools. …
in order to achieve the administration’s goal of eliminating the racial discipline gap, schools that currently have many disruptive students and strict discipline policies will have to relax those policies.
Which brings us to Kinsler’s most important discovery: easing discipline policies in such schools causes overall student achievement to fall.