WASHINGTON — The Justice Department declined on Tuesday to defend a congressional ally of former President Donald J. Trump in a lawsuit accusing them both of inciting supporters at a rally in the hours before the Jan. 6 storming of the Capitol.
Law enforcement officials determined that Representative Mo Brooks, Republican of Alabama, was acting outside the scope of his duties in an incendiary speech just before the attack, according to a court filing. Mr. Brooks had asked the department to certify that he was acting as a government employee during the rally; had it agreed to defend him, he would have been dismissed from the lawsuit and the United States substituted as a defendant.
“The record indicates that Brooks’s appearance at the Jan. 6 rally was campaign activity, and it is no part of the business of the United States to pick sides among candidates in federal elections,” the Justice Department wrote.
“Members of Congress are subject to a host of restrictions that carefully distinguish between their official functions, on the one hand, and campaign functions, on the other.”
The Justice Department’s decision shows it is likely to also decline to provide legal protection for Mr. Trump in the lawsuit. Legal experts have closely watched the case because the Biden Justice Department has continued to fight for granting immunity to Mr. Trump in a 2019 defamation lawsuit where he denied allegations that he raped the writer E. Jean Carroll and said she accused him to get attention.
Such a substitution provides broad protections for government officials and is generally reserved for government employees sued over actions that stem from their work. In the Carroll case, the department cited other defamation lawsuits as precedent.
The Brooks decision also ran counter to the Justice Department’s longstanding broad view of actions taken in the scope of a federal employee’s employment, which has served to make it harder to use the courts to hold government employees accountable for wrongdoing.
Mr. Brooks did not immediately respond to a request for comment.
Lawyers for the House also said on Tuesday that they declined to defend Mr. Brooks in the lawsuit. Given that it “does not challenge any institutional action of the House,” a House lawyer wrote in a court filing, “it is not appropriate for it to participate in the litigation.”
The Justice Department and House filed their briefs on Tuesday, the deadline set by Judge Amit P. Mehta of the Federal District Court for the District of Columbia. The lawsuit, filed in March by Representative Eric Swalwell, Democrat of California, accuses Mr. Brooks of inciting a riot and conspiring to prevent a person from holding office or performing official duties.
Mr. Swalwell accused Mr. Brooks, Mr. Trump, his son Donald Trump Jr. and his onetime personal lawyer Rudolph W. Giuliani of playing a key role in inciting the Jan 6. attack during a rally near the White House in the hours before the storming of the Capitol.
Citing excerpts from their speeches, Mr. Swalwell accused the men of violating federal law by conspiring to prevent an elected official from holding office or from performing official duties, arguing that their speeches led Mr. Trump’s supporters to believe they were acting on orders to attack the Capitol.
Mr. Swalwell alleged that their speeches encouraged Mr. Trump’s supporters to unlawfully force members of Congress from their chambers and destroy parts of the Capitol to keep lawmakers from performing their duties.
During the rally, Mr. Brooks told attendees that the United States was “at risk unlike it has been in decades, and perhaps centuries.” He said that their ancestors “sacrificed their blood, their sweat, their tears, their fortunes and sometimes their lives” for the country.
“Are you willing to do the same?” he asked the crowd. “Are you willing to do what it takes to fight for America?”
Mr. Swalwell said defendants in his lawsuit had incited the mob and had continued to stoke false beliefs that the election was stolen.
“As a direct and foreseeable consequence of the defendants’ false and incendiary allegations of fraud and theft, and in direct response to the defendants’ express calls for violence at the rally, a violent mob attacked the U.S. Capitol,” Mr. Swalwell said in his complaint. “Many participants in the attack have since revealed that they were acting on what they believed to be former President Trump’s orders in service of their country.”
In June, Mr. Brooks asked that the Justice Department defend him in the case. He cited the Westfall Act, which essentially substitutes the Justice Department as the defendant when federal employees are sued for actions deemed within the scope of their employment, according to a court document.
He described his speech on Jan. 6 as part of his job, saying that his duties include delivering speeches, making pronouncements on policy and persuading lawmakers.
The Justice Department rejected that assertion.
“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 — and thus is not the sort of conduct for which the United States is properly substituted as a defendant under the Westfall Act,” the department wrote. “Brooks does not argue otherwise. Instead, he denies the complaint’s allegations that he conspired to incite the attack on the Capitol.”
Mr. Trump has not sought to have the government substitute for him as a defendant in the lawsuit under the Westfall Act. But he has argued in court filings that the statements he made on Jan. 6 are covered by broad immunity, that he could not be sued for making them and that the lawsuit violated his free speech rights.
Should a judge deny Mr. Trump’s claims, he could ask the Justice Department to intervene on his behalf. But its decision in Mr. Brooks’s case lowered the chances that it would comply.