A Texas jury took only 17 minutes to convict parolee and former mechanic Duane Buck of gunning down his ex-girlfriend and a man at her Houston apartment, then deliberated about four hours before deciding he should be put to death. Now nearly two decades later, the U.S. Supreme Court is being asked to look for a third time at whether the death sentence the jury gave Buck was tainted by testimony and evidence related to the fact he is black. “Injecting race into a capital sentencing proceeding is not only wholly improper, it poses a special risk of harm to...