This is an archived article that was published on sltrib.com in 2017, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

FBI Director James Comey's testimony Monday that the bureau is investigating possible connections between Donald Trump's campaign and Russia sparked complaints among Democrats that he should've said so back in July. But that gets things exactly backward. The time for the FBI director to disclose an investigation is not when it's just getting started, and he chooses to make the announcement unilaterally. It's when the investigation is under way, and Congress is asking for a sworn statement in reply.

Comey's historic error in announcing in October that the investigation into Hillary Clinton's email server would be reopened because of possible new evidence was that he acted on his own, and before any meaningful investigation had actually happened. A summer or fall announcement of the Russia investigation would've been just as bad.

As a general matter, of course, it's inappropriate for law enforcement to comment on ongoing investigations of any kind, not just those of political significance. In that sense Comey had it right in January when he told the Senate Intelligence Committee that he "would never comment on investigations — whether we have one or not — in an open forum like this," and therefore wouldn't "answer one way or another" with respect to the question of an investigation into the Trump campaign's possible Russia ties.

The reason not to comment lies with the tremendous power of the investigative wing of the modern state. Just to be investigated by the government is to be cast under suspicion.

What's more, the aura of accusation can itself be politically harmful. That's a key reason President Trump himself was so wrong to accuse Barack Obama of "wiretapping" his campaign headquarters. An accusation not backed up by evidence is government by innuendo.

If the president shouldn't make accusations without evidence, neither should the director of the Federal Bureau of Investigation. And there's no way to have evidence if the investigation hasn't really taken place. The crucial aspect of Comey's error in the Clinton case was that he said there was going to be an investigation when a few days of inquiry would have revealed — as it indeed did reveal — that there was nothing new to be investigated.

Beyond the timing lies the question of who authorizes or asks for the disclosure.

Comey made an enormous mistake by acting on his own authority and under his own impetus by announcing the reopening of the Clinton investigation. Regardless of his motives, which very possibly could have been well-meaning, it was beyond the ambit of the FBI director to decide what the public needed to know on the eve of an election. Whether Comey admitted it to himself or not, he was interfering in electoral politics, a cardinal constitutional sin for a law enforcement official.

In contrast, the statements Comey has now made before the House Intelligence Committee were delivered in a very different context. The public, or at least some part of it, has been clamoring to know whether the FBI is investigating the Trump campaign. Duly elected officials from the legislative branch are asking for Comey's testimony.

Although Comey's testimony was in essence voluntary — witness his refusal to testify on the same topic before the Senate committee a couple of months back — it still matters that another branch of government was asking for the information. Even if it might have been possible for Comey to fight a congressional subpoena successfully, his willingness to answer reflects respect for Congress's supervisory authority over the executive branch.

What's more, we're not in the middle of a campaign. Although Comey's answer certainly has substantial political implications, it's unlikely to sway an electoral outcome at this point in the voting cycle.

The upshot is that if we were to draw a general principle about when it's OK for the FBI director to reveal the existence of an investigation, it would probably be something like: when there's been time for the investigation to develop, Congress is asking, and the answer won't have any imminent electoral effect.

None of these conditions existed when Comey threw Clinton under the bus. And they wouldn't have existed either when the FBI investigation of Trump began in July. He was right to disclose the FBI investigation now. But he would've been wrong to do so on his own initiative in the summer.

Taking those views together should enable FBI directors to do better in the future.

- Feldman is a Bloomberg View columnist. He is a professor of constitutional and international law at Harvard University and was a clerk to U.S. Supreme Court Justice David Souter. His books include "Cool War: The Future of Global Competition" and "Divided by God: America's Church-State Problem — and What We Should Do About It."