In this case, Comey ignored those rules to editorialize about what he called carelessness by Clinton and her aides in handling classified information, a statement not grounded in any position in law. He recklessly speculated that Clinton’s email system could have been hacked, even while admitting he had no evidence that it was. This conjecture, which has been the subject of much debate and heated allegations, puts Clinton in the impossible position of having to prove a negative in response.

In several instances, Comey made assertions that are outside the authority of the FBI. He inserted himself into a long-standing bureaucratic battle between the State Department and the FBI and intelligence agencies, making claims about classification practices at the State Department that do not fall under his jurisdiction. He raised the possibility of administrative sanctions that could be taken, another decision that is not his to make — any such sanctions, if appropriate, would be decided by the State Department, not the director of the FBI.

He also substituted his judgment for that of prosecutors. Career prosecutors at Justice have been working hand in hand with FBI agents on the case, even joining the interview with Clinton. While it is hard to imagine they would have reached a different conclusion about the appropriateness of charges, they deserved the ability to make that decision privately, in consultation with the FBI, rather than hear the agency’s recommendation at the same time the public did.

Comey argued that his statement was appropriate because this case was a matter of unusual public interest. But the department investigates cases involving extreme public interest all the time — suspected terrorist acts, alleged civil rights violations by police and possible crimes by financial institutions, for example. It is for precisely these situations that the rules exist, so that the department cannot speak outside the bounds of court when it does not bring charges.

Imagine a situation in which the Obama Justice Department investigates major conservative activists such as the Koch brothers for possibly violating the law, but finding no reason to bring charges, the attorney general holds a news conference to outline all of the ways in which she finds their conduct deplorable. A Republican attorney general declining to bring charges against union officials but publicly excoriating their behavior would be similarly objectionable.