The congressional committee investigating the Jan. 6 riot at the U.S. Capitol last year still hasn’t started overdue public hearings. But it it has now produced an important legal opinion from a federal judge stating that the “illegality” of the course of action President Donald Trump embarked upon after losing the 2020 election “was obvious.”

The opinion does not put Trump or anyone else in immediate legal jeopardy, although it might put pressure on the Department of Justice to look seriously at the possibility of future indictments. But it’s a significant moment nonetheless.

Judge David O. Carter wrote of Trump and John Eastman, a lawyer who had plotted with the former president on how to overturn the election and was now attempting to shield emails from the House Select Committee to Investigate the Jan. 6 Attack:

“Dr. Eastman and President Trump launched a campaign to overturn a democratic election, an action unprecedented in American history. Their campaign was not confined to the ivory tower—it was a coup in search of a legal theory. The plan spurred violent attacks on the seat of our nation’s government, led to the deaths of several law enforcement officers, and deepened public distrust in our political process... If Dr. Eastman and President Trump’s plan had worked, it would have permanently ended the peaceful transition of power, undermining American democracy and the Constitution. If the country does not commit to investigating and pursuing accountability for those responsible, the Court fears January 6 will repeat itself.”

Carter’s ruling that Eastman was not entitled to withhold the emails because lawyer-client privilege does not apply to felonious behavior is very much an Emperor’s New Clothes moment.

Unlike Watergate, the Iran-Contra affair, and many other important scandals of the past, the investigation into Trump’s efforts to illegally overturn the 2020 election did not need to uncover well-hidden secrets in order to get to the truth, although there were some secrets — including Eastman’s road map for how to steal the election. But the bulk of what Trump did was in plain sight. So as important as it is to fill in all the details, the most important thing is what Judge Carter did on Monday: accurately labeling Trump’s actions.

It’s not clear what the effect of Carter’s opinion might be. It won’t change the minds of Trump’s strongest supporters, who simply believe his false claims and have convinced themselves that the election was stolen from them despite Trump’s failure to produce any significant evidence to back up the lie. Nor will it affect partisan Democrats, who already believed what Carter said. It could, however, have some influence on two groups that have been convinced since the Jan. 6 attacks that what Trump did was wrong but are tempted to let it recede into the past — groups that might otherwise be open to an argument that there’s no point in beating the dead horse of this scandal and the former president’s misconduct.

One of these groups is the nonpartisan media. The reporters and editors, correspondents and producers of outlets affiliated with neither party like to think of themselves as neutral, and feel uncomfortable treating anyone (much less a former president) as a criminal and an obvious opponent of democracy. Especially on their own authority. Carter’s decision may give them more license than they’ve had to state flat-out what they already probably knew.

The other group is those Republican party actors who have tried to tread a middle ground on Trump. It’s hard to know exactly how large that group is, but remember that seven Republican senators voted in February 2021 to convict Trump during his second impeachment and several others said they would have joined them had Trump still been in office.

It’s not just that Carter may remind them of what they believed last year. It’s that he’s issuing a warning that this issue isn’t going away, and that they may wind up having publicly state their opinions about it again. That might push them to align more openly with Trump. But if they still have the same views they had last year and had been hoping to duck the topic, they might also side more openly against him.

That is also one of the reasons why an extended series of public hearings should have started months ago, and still would be a good idea. It doesn’t have to change minds; it only has to reinforce what most opinion leaders, as well as most voters, believed back in January 2021. The sooner the better. Public hearings about Trump and his allies are unlikely to help Democrats in the November midterm elections, but the closer the hearings are to November, the easier it will be for Republicans to dismiss them as a form of partisan electioneering.

To be fair, the subpoena of Eastman has now produced the kind of public education that the committee should be aiming for. Too often, the news the committee produces is about invitations to testify (behind closed doors, at least for now) and subsequent fights over compliance. Now there’s one significant story about presidential misbehavior and lawbreaking.

Richard Nixon once said, “People have got to know whether or not their president is a crook.” The same applies to former presidents. Especially those who are still involved in politics, and actually seeking another term in the White House. One judge’s opinion hardly settles the matter, but it’s a bit of official confirmation that Trump’s denials are worth about as much as Nixon’s were.

Jonathan Bernstein is a Bloomberg Opinion columnist covering politics and policy. Visit bloomberg.com/opinion