Whatever that means. Mr. Comey’s gnomic, ex cathedra distinction between Mrs. Clinton’s “extremely careless” handling of classified information and the “grossly negligent” standard that would have put her in legal jeopardy probably saved her candidacy. Friday’s letter to Congress, raising “there’s-gotta-be-something-there” suspicions, may yet save Mr. Trump’s.

These aren’t partisan acts. They are self-regarding ones. Mr. Comey is a familiar Washington type—the putative saint—whose career is a study in reputation management. He went after investment banker Frank Quattrone. He threatened to resign from the Bush administration over its warrantless wiretap program. He vouchsafed the case against Steven J. Hatfill, the virologist accused of the 2001 anthrax mail attacks, in internal White House deliberations. He appointed his close friend Patrick Fitzgerald to investigate the leak of CIA analyst Valerie Plame’s name.

One common thread in these cases is that Mr. Comey was always on the right side of Beltway conventional wisdom. The second is that he was consistently on the wrong side of justice.