James Comey has finally admitted some “sloppiness” over the surveillance warrant for former Trump campaign aide Carter Page. The former FBI director should re-read Inspector General Michael Horowitz’s report because it lays out a record of willful incuriosity about Christopher Steele and his dossier that is hard to credit as mere incompetence.

The report quotes Bill Priestap, a key FBI player in the 2016 Crossfire Hurricane probe into the Trump campaign, that the FBI had “concerns” about Mr. Steele’s “reporting the day we...