Laurence H. Tribe is Carl M. Loeb University Professor emeritus and a professor of constitutional law emeritus at Harvard Law School.

Donald Trump managed to evade legal accountability throughout his presidency. That might be about to change — and the newest sign comes in a brief filed by the Justice Department. It doesn’t directly address the former president, yet has ominous implications for his ability to avoid responsibility for his role in the Jan. 6 insurrection.

The Justice filing came in a lawsuit in which Rep. Eric Swalwell (D-Calif.) and a number of Capitol Police officers have sued Trump and others for their roles in the insurrection. One of those named in the suit, Rep. Mo Brooks (R-Ala.), claimed that he is immune from personal liability under a law known as the Westfall Act, which shields federal officials acting within the scope of their employment.

U.S. District Judge Amit P. Mehta asked for the Justice Department’s position, and, in a filing Tuesday, the department resoundingly rejected Brooks’s view. This is a correct — indeed, an unavoidable — interpretation of the law. It is a view that is directly relevant to Trump’s potential liability in the Swalwell lawsuit and other pending litigation, and a welcome departure from the position endorsed by the Justice Department in the defamation lawsuit filed against Trump by writer E. Jean Carroll.

In the Carroll case, the department accepted Trump’s argument that his disparaging comments about Carroll while he was president were within the broad scope of his responsibilities. Even recognizing the department’s legal duty to defend federal officials and to consider the implications of its actions for future presidents facing charges of wrongdoing, I strongly disagreed with that decision: Accusing someone of lying about your actions before you became president, as Trump did with Carroll’s rape accusation, cannot automatically fall within the scope of your presidential employment.

In the Swalwell suit, the department adopted a narrower and, I believe, more legally defensible, stance about when federal employees are immune from suit.

The department first invoked Brooks’s own “defense” that his appearance at Trump’s Jan. 6 rally before the insurrection was “campaign activity,” not part of his official position: He was trying to get Trump declared the winner of the 2020 election and to promote GOP wins in 2022 and 2024. That was, the department properly concluded, political activity, not remotely covered by any immunity.

Even if Brooks’s appearance was not deemed campaign-related, the department added, he still is not entitled to immunity because he was accused of violating federal law — by definition, not part of his job. “Instigat[ing] a violent attack on the U.S. Capitol … plainly could not be within the scope of federal employment,” the brief said.

Where does that leave Trump, who is also a defendant in the lawsuit and has also asked that it be dismissed? Not in great legal shape, in my view.

Granted, the distinction between campaign and official duties could be harder to make in the case of a president, whose role inextricably combines both aspects of the job.

Nonetheless, the department’s forceful conclusion was that Brooks’s alleged actions — conspiring to “injure members of Congress and Vice President Pence,” “disrupt the peaceful transfer of power,” or otherwise ensure Trump’s installation as the next president — cannot qualify as part of Brooks’s official job. That irrefutable logic is equally applicable to Trump.

Tellingly, the department’s brief said, “Inciting or conspiring to foment a violent attack on the United States Congress is not within the scope of employment of a Representative — or any federal employee,” a category manifestly including the president himself.

Trump, in asking the judge to dismiss the case against him, referred to the Westfall Act in a footnote, arguing that “the allegations arose out of his [exercise] of political speech, clearly within the scope of his employment (i.e., ensuring the faithful execution of the laws and carrying out his other Constitutional duties).” Then he made an even more jaw-dropping claim: “The Constitution Forecloses This Court from Exercising Jurisdiction Over President Trump for Actions Taken During His Presidency.”

In defense of this audacious assertion, Trump’s lawyers cite the Supreme Court’s 1982 decision in Nixon v. Fitzgerald, which held that presidents are immune from civil suit for most official actions. But the court in that case made clear it wasn’t addressing civil suits based on specific federal statutes, as the Swalwell suit is. It also articulated a vital limiting principle: actions that do not fall “within the outer perimeter of [the president’s] duties of office” can subject the president to liability.

“A political speech by the President is not at the ‘outer perimeter’ of his duties — it is at the dead center,” the Trump lawyers claim. “It is well recognized that rousing and controversial speeches are a key function of the presidency.”

But, as Swalwell and other plaintiffs argue, Trump went far beyond giving a controversial speech. He insisted that he had won reelection regardless of what anyone said and stirred up a violent, partly armed and visibly angry mob and aimed it at the Capitol to disrupt the official counting of electoral votes. He stood by and even praised the mob as it grew violent, rejecting requests to help those under assault.

Inciting an attack on Congress “is not within the scope of employment of … any federal employee,” the department reminded us, and Trump, in its brief. That single word, “any,” marks the difference between a president and a dictator.