Judge Mark L. Wolf, writing in The Atlantic, said he was stepping down to defend against the “assault on the rule of law” by President Trump, who he accused of “targeting his adversaries.”A federal judge warned of an “existential threat to democracy” in a searing first-person essay published on Sunday, saying he had stepped down from the bench to speak out against President Trump. He accused Mr. Trump of “using the law for partisan purposes, targeting his adversaries while sparing his friends and donors from investigation, prosecution, and possible punishment.”The judge, Mark L. Wolf, wrote in The Atlantic magazine that...