The war between the president and the nation’s law enforcement apparatus is unlike anything America has seen in modern times. With a special counsel investigating whether his campaign collaborated with Russia in 2016 and whether Mr. Trump obstructed justice in 2017, the president has engaged in a scorched-earth assault on the pillars of the criminal justice system in a way that no other occupant of the White House has done…

“I can’t think of another time when this has happened,” said Jack L. Goldsmith, a Harvard law professor who headed the Justice Department’s Office of Legal Counsel under President George W. Bush. “And it’s happening largely because the president is being investigated.”…

“Thanks to this rhetoric, there is a subset of the public that won’t believe what comes out of the Mueller investigation,” said Christopher Hunter, a former F.B.I. agent and prosecutor who left the Justice Department at the end of last year. Mr. Hunter said he worried that juries might be more skeptical of testimony from agents even in criminal trials unrelated to Mr. Trump. “All it takes to sink a case,” he said, “is for one juror to disbelieve the F.B.I.”