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.
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…