An investigation into Comey. Finally.

The Justice Department inspector general’s office said on Thursday it would open an investigation into the decision in October by James B. Comey, the F.B.I. director, to inform Congress about a new review in the Hillary Clinton email investigation — a move Mrs. Clinton has said cost her the election.

The inquiry is not a blow for Mr. Comey only. It also draws negative attention again to the F.B.I. on an issue that agents had hoped was behind them.

The inspector general’s office said the investigation had come in response to complaints from members of Congress and the public about actions by the F.B.I. and the Justice Department during the campaign that might be seen as politically motivated.

Chief among those actions was the decision by Mr. Comey to write two letters on the email matter within 11 days of the election, creating a wave of damaging news stories about the controversy late in the campaign. In the end, the new emails that the F.B.I. reviewed — which came up during an unrelated inquiry into Anthony D. Weiner, the estranged husband of a top Clinton aide, Huma Abedin — proved irrelevant.


Graphic | These Are the Bad (and Worse) Options James Comey Faced When federal officials concluded their investigation into Hillary Clinton’s use of a private email server as secretary of state, the F.B.I. director, James B. Comey, had a decision to make on how to announce that news. The choices he made in July set the F.B.I. on the path toward the predicament it faces today.
But the inspector general, Michael Horowitz, said he would also be examining other issues, including whether the deputy director of the F.B.I., whose wife ran as a Democrat for the Virginia State Senate, should have recused himself from any involvement in the Clinton email investigation. Another issue is whether a top Justice Department official gave information to the Clinton campaign.

The ramifications of the investigation were not immediately clear. Mr. Horowitz has the authority to recommend a criminal investigation if he finds evidence of illegality, but there has been no suggestion that Mr. Comey’s actions were unlawful. Rather, the question has been whether he acted inappropriately, showed bad judgment or violated Justice Department guidelines.

The Justice Department and the F.B.I. have a longstanding policy against discussing criminal investigations. Another Justice Department policy declares that politics should play no role in investigative decisions. Both Democratic and Republican administrations have interpreted that policy broadly to prohibit taking any steps that might even hint at an impression of partisanship.

It is extraordinarily rare for the inspector general to publicly disclose its investigations, particularly in such detail. That means that the inspector general has now broken with policy and announced details of an investigation into whether Mr. Comey broke with policy and announced details of an investigation.

Mr. Comey’s actions attracted criticism from members of both parties. Some criticized him for releasing the letter at the height of the campaign. Donald J. Trump, on the other hand, accused him of being part of a rigged system because the F.B.I. cleared Mrs. Clinton of criminal liability.