The criticism of the Department of Justice continues to grow: Detractors see the department as too far behind the Jan. 6 committee. They want to know why Attorney General Merrick Garland and the Justice Department have yet to come forward with a serious criminal charge against Donald Trump.

These gloomy observations miss at least one crucial point: There is a gap in the committee’s development of the Jan. 6 evidence for the most serious yet fitting charge against Trump. And it seems likely that only the Justice Department can fill it.

First, remember that the Justice Department may be much further along than we know; its work initially is always largely opaque.

The House hearings aim to present a general narrative of Team Trump’s attempt to undo President Biden’s victory, along with the facts to back it up. The Justice Department, on the other hand, needs to develop a legal case consisting of admissible evidence proving criminal guilt beyond a reasonable doubt, and if possible beyond Republican cavil as well.

What crime exactly? Here’s another important difference between the department’s task and Congress’. The committee’s work has given rise to a sort of parlor game of “name that Trump crime” among commentators, everything from manslaughter to destruction of federal property. That won’t cut it for the Justice Department.

Even assuming that the department could prove any number of offenses on the part of Trump, Garland would not take the unprecedented step of prosecuting a former president unless the charge involved a grave crime against the U.S. Most likely, that charge would be seditious conspiracy.

In the federal criminal code, seditious conspiracy is defined, in part, as two or more people agreeing to “oppose by force” the government’s authority or agreeing “by force to prevent, hinder, or delay the execution of any law of the United States.” It doesn’t matter if they succeed; the crime is in the agreement.

Although the committee has presented ample, even voluminous, evidence of Trump’s role in the events of Jan. 6, to date it has produced only circumstantial evidence of the all-important element of an agreement between Trump and a co-conspirator.

The “will be wild” Trump tweet inviting his followers to Washington; Steve Bannon’s declaration that “all hell” would “break loose” on Jan. 6; and Rudy Giuliani’s statement to Cassidy Hutchinson on Jan. 2 that Jan. 6 would be wild, seconded by her boss, White House Chief of Staff Mark Meadows, all speak to the likelihood but not the certainty that Trump conspired with one or more persons to “prevent, hinder or delay” Congress’ certification of the election.

It’s theoretically possible to prove a case of seditious conspiracy based on circumstantial evidence, but we can be sure that won’t be enough for the prosecution of a former president. Absent a major new revelation from the committee, we must rely on the Justice Department to supply the critical agreement element.

The traditional, and most effective, way for prosecutors to nail a charge against someone like Trump would be to leverage the cooperation of an alleged co-conspirator – in this case, a Giuliani, a Bannon or a Meadows, perhaps – with a promise of immunity. The department has that kind of power; a congressional committee does not.

Within its brief, the Jan. 6 House Select Committee has done a splendid job. But it will take more than a simple handoff of the committee’s findings to the Justice Department to set up a successful prosecution of Trump and his cronies.

The Justice Department’s critics are wrong to conclude that Garland’s work has been done for him in Congress. Garland deserves the presumption that, as promised, he is going after insurrectionists “at all levels,” and that the department will do the heavy lifting to induce a loyalist to turn on the former president.

Unless and until Garland succeeds, Trump, by virtue of the committee’s outstanding work, may stand guilty in the public’s mind and in the judgment of history, but there’s no holding him criminally accountable in a court of law.