There was once an honorable tradition of resignations from government service. Cy Vance stepped down as Jimmy Carter’s Secretary of State after each man lost confidence in the other’s judgment. George Tenet resigned as George W. Bush’s CIA director in the wake of the Iraq WMD intelligence debacle.

Now it behooves James Comey to do the same. The FBI director lost the confidence of millions of Americans last summer by using semantic sophistry and bureaucratic legerdemain to exonerate Hillary Clinton from charges of mishandling...