Prosecutors would face substantial hurdles in potentially pursuing charges against Ms. Carroll, who twice won cases against Donald Trump, or the billionaire who helped pay her lawyers.
The ruling was a blow to both President Trump, who had voluntarily dismissed the suit last week, and to the Justice Department, which used the suit to establish a fund likely intended for Trump allies.
In a stern order on Friday, a judge said that she wanted to investigate the circumstances surrounding President Trump’s efforts to settle the lawsuit in a way that benefited him and his allies.
The ruling allowed the Trump administration to continue to pursue changes that include enlisting the Postal Service in checking voters against a national database.
Ms. Carroll, who prevailed in a civil trial after accusing President Trump of sexual abuse, is the latest target in a Justice Department campaign going after his perceived enemies.
The surprising demand to appear at a hearing suggested new concern about the Trump administration’s efforts to repay the full $166 billion owed from illegally imposed tariffs.
The actor Matthew Perry was found unresponsive in a hot tub at his home in Los Angeles on Oct. 28, 2023. His assistant had injected him with at least three shots of ketamine that day.
Daniela Klette, 67, was part of the Red Army Faction, which attacked American and capitalist interests until the 1990s. She was convicted of robberies committed later to finance life as a fugitive.
Republican leaders in the state have asked the justices to clear the way for a congressional map that a lower court found discriminated against Black voters.
The plaintiffs had sought a temporary restraining order, arguing that the map violated a state ban on partisan gerrymandering that voters passed in 2010.
Republican lawmakers, who hold supermajorities in the State House and Senate, passed the new map last month at the urging of Gov. Ron DeSantis, a Republican.
Florida officials had asked the justices to hear a lawsuit accusing California and Washington of improperly granting licenses to an immigrant accused in a fatal crash.
Harjinder Singh being escorted by Lt. Gov. Jay Collins of Florida and members of law enforcement in Stockton, Calif., in August. Mr. Singh is accused of causing a fatal crash in Florida by making an illegal U-turn.
A group of immigration judges in 2020 challenged work-related restrictions on their public speaking engagements, saying they violated their free speech rights.
Alabama is likely to appeal the ruling, which stops an effort to use a new congressional map that would likely cost Democrats a majority-Black district.