When I teach about the history of the segregated South, sometimes my students remark that things are just as bad now as they were then, that conditions for Black Americans are still as bleak for too many. Often my response is that if someone were to hang me or them by that tree in front of the building, someone would come. The law would investigate. Our citizenship would matter in at least that crucial way.

 This month is challenging that assumption. When Trayvon Martin was murdered for looking "suspicious", killed without any pretense of a trial, the police failed to come.