Let me start by saying that I do not dissent from FBI Director James Comey's decision to give the remarkably fulsome account we saw this week of the Hillary Clinton email investigation, both in his lengthy statement Tuesday and, particularly, in his marathon testimony yesterday. Jack has discussed his reasons for doing so. And Comey has too. In his testimony yesterday, he made clear that the extraordinary nature of a criminal investigation of a person who is about to be nominated for President by a major party demanded a degree of transparency that is atypical and that would satisfy reasonable people that the bureau had followed the regular order. That seems right. He was in an impossible position, made far more so by the almost mind-boggling decision of Bill Clinton to publicly compromise the attorney general. Comey's testimony was extraordinary in its candor, both as to his reasoning on his decision not to recommend prosecution and as to the often-minute details of the FBI's findings. To my mind, it was also entirely persuasive.

That said, I think it's important to stress that this is really not the way we want major investigations to be closed out in the future.

There is something horrible about watching a senior government official, who has used the coercive investigative capacities of the federal government, make public judgments about a subject's conduct which the Justice Department is not prepared to indict. There is something even more horrible about a hearing in which individual members of Congress feel entitled to pick over the details of that conduct, asking about whether specific questions were asked by the FBI of specific witnesses and subjects and asking whether specific lines of inquiry were followed.

As a general matter, when prosecutors and investigators decline to indict someone, we don't want a report, much less congressional oversight of the unindicted conduct. We want them to shut the heck up.

This point is rooted in important civil liberties concerns. We don't give the FBI the power to investigate people so that it can report on their characters or behavior, so that the FBI director can pronounce on the truthfulness of their public utterances (which Comey endeavored not to do and yet inevitably did repeatedly simply by reporting his findings). And we don't give congressional committees the power of oversight, generally speaking, so that they can review individual prosecutorial decisions by flyspecking the details of the conduct of particular investigations vis a vis individual subjects. We give the FBI these powers so that it can investigate crimes. And if the Justice Department is not going to prosecute someone, it generally has no business talking about the conduct of that person's affairs.

Public officials have always tested this norm because we have sometimes used criminal investigations as a proxy to make determinations beyond the strictly prosecutorial: Is the subject fit for office? How should voters think about what this person did? The independent counsel law, as a result, had a provision for a "final report"—a report which often explained non-prosecution decisions. The Justice Department has sometimes issued similar reports in other matters of great public interest. But I can think of no case in which a chief investigator has gone up to Congress to discuss the details of his investigation, and investigative findings concerning unindicted individuals, and spent many hours discussing what conduct was found, what conduct was not found, why he decided not to proceed, and what facts would have had to be different for him to decide otherwise.

As I say, this may well be justified in the specific, extraordinary context of a major party presidential nominee whose conduct was really bad but against whom an indictment would be wrong in an investigation taking place during a presidential campaign in which she is asking for a further investment of public trust. But it is emphatically not the way you want the FBI generally to do business—even in high profile cases involving public figures. Imagine, for example, that the Justice Department had decided not to indict Senator Bob Menendez or former Virginia Governor Bob McDonnell. It would be grossly wrong to issue a major statement on their conduct or about the investigative findings made concerning them. It would be even more wrong for Congress to demand an hours-long Q&A on the juicy details or for the FBI to oblige.

Imagine, conversely, that the FBI and the Justice Department had—after a senator disclosed the contents on 9/11 of US government signals intelligence intercepts concerning the attacks—sent an investigator up to the Hill to discuss in detail the decision not to bring a criminal case against that senator (who is still in office, by the way). It would have been very wrong. Once the Justice Department decides it's not going to prosecute someone for something, it has no business talking about that person's behavior.

Comey himself acknowledged the potential slippery slope at one point, noting that his testimony and transparency in this instance was a precedent he hoped to confine to similar circumstances in the future—and that he expected those to be rare, if not a null set. I hope very much he and his successors are able to do that. It would be a terrible thing if the costs of FBI investigation for the unindicted were a kind public truth commission in which the conduct of those not prosecuted gets publicly judged by the executive branch and any committee with jurisdiction to demand answers from it.