No one has cultivated an image of public virtue better than FBI director James Comey, so he was in high dudgeon Wednesday when mere mortals like elected Members of Congress challenged his investigation of Hillary Clinton’s email violations as Secretary of State.

“You can call us wrong, but don’t call us weasels. We are not weasels,” Mr. Comey declared Wednesday at a House Judiciary Committee hearing. Weasels or not, Mr. Comey did little to rebut the suspicion that he handled the Clinton probe with tender loving political care.

Recall that in July Mr. Comey held a remarkable press conference in which he announced that Mrs. Clinton shouldn’t be prosecuted for mishandling classified information. But it isn’t his job to make prosecutorial decisions. That’s the duty of Justice Department prosecutors. Mr. Comey’s unprecedented declaration had the effect of letting Justice officials off the hook.

Yet there was Mr. Comey on Wednesday passing the buck to the same Justice Department. Republicans wanted to know how and why Clinton aides Cheryl Mills and Heather Samuelson had been granted immunity from prosecution. Don’t ask Saint Jim.

That was “a decision made by the Department of Justice” and the FBI wasn’t “part of those discussions,” he said. Seriously? The FBI was willing to bug out of a decision on immunity that would be directly relevant to its ability to collect evidence?