According to the complaint, when Congress considered the possibility of applicants being asked to apply for asylum in a third country, it created narrow exceptions under which that would occur: If the immigrant was firmly resettled in another country, or if the United States entered into a formal agreement with a third country that would give immigrants a safe and meaningful opportunity to apply in that country.

The administration announced the new policy despite the fact that Guatemala and Mexico have not signed onto the plan — meaning those countries have made no assurances that they will grant asylum to migrants who are headed to the United States.

The Trump administration has been negotiating fruitlessly for months with Guatemala and Mexico in the hope of reducing the number of asylum applicants arriving in the United States. Talks with Guatemala broke down and the country’s president, Jimmy Morales, backed out of a meeting that had been scheduled on Monday at the White House. Talks with Mexico remain in flux.

“Even a bilateral agreement with those countries would not suffice because Congress made clear that the third-party country would have to ensure a safe and meaningful opportunity to obtain asylum,” said Lee Gelernt, the deputy director of the American Civil Liberties Union’s Immigrants’ Rights Project, who is the lead lawyer in the case.

“We hope to swiftly enjoin this policy before it does real harm to families and others fleeing danger and seeking safe haven in the United States,” he added.

In November, a federal court blocked a prior attempt by the administration to restrict asylum that Mr. Gelernt described as “similar but less extreme than the latest one.”

That case resulted in an unusual public disagreement between President Trump and Chief Justice John Roberts over the role of judges and whether there was such a thing as an “Obama judge.”