In a highly unusual legal move, lawyers for the Justice Department said in court papers that Mr. Trump was acting in his official capacity as president when he denied ever knowing Ms. Carroll and thus could be defended by government lawyers — in effect underwritten by taxpayer money.
Though the law gives employees of the federal government immunity from most defamation lawsuits, legal experts said it has rarely, if ever, been used before to protect a president, especially for actions taken before he entered office.
“The question is,” said Steve Vladeck, a University of Texas law professor, “is it really within the scope of the law for government lawyers to defend someone accused of lying about a rape when he wasn’t even president yet?”
The motion also effectively protects Mr. Trump from any embarrassing disclosures in the middle of his campaign for re-election. A state judge issued a ruling last month that potentially opened the door to Mr. Trump being deposed in the case before the election in November, and Ms. Carroll’s lawyers have also requested that he provide a DNA sample to determine whether his genetic material is on a dress that Ms. Carroll said she was wearing at the time of the encounter.
Ms. Carroll’s lawyer said in a statement issued Tuesday evening that the Justice Department’s move to intervene in the case was a “shocking” attempt to bring the resources of the United States government to bear on a private legal matter.