Experts said the high court appeared to be taking an aggressive step by intervening in the high-profile issue at this stage but cautioned that the order does not address major underlying questions about Trump’s legal authority to use the Alien Enemies Act to remove migrants from the United States.

Georgetown Law professor Steve Vladeck called the Supreme Court’s involvement overnight “a sign that a majority of the justices have lost their patience with the procedural games being played by the Trump administration,” at least as it relates to the cases involving the Alien Enemies Act.

Earlier this month, a divided Supreme Court said in a different case that the administration could continue to invoke the Alien Enemies Act to try to deport alleged gang members, but the justices were unanimous in saying that detainees must first have an opportunity to challenge their detention in the jurisdiction where they are being held.

The Supreme Court’s latest order came after hours of frenzied litigation Friday, as attorneys for the detainees petitioned courts in North Texas and Washington, as well as the U.S. Court of Appeals for the 5th Circuit based in New Orleans, hoping one of them would step in to stop the deportations before it was too late.

In its order early Saturday, the Supreme Court said it would take further action after the 5th Circuit had weighed in. It asked the solicitor general, which argues on behalf of the federal government, to respond to the ACLU’s claims after the 5th Circuit ruled on the matter. The 5th Circuit issued its own ruling around the same time, with a three-judge panel of that court denying the ACLU’s emergency request to block the deportations and chiding its lawyers for coming to them before a lower court had ruled on the issue.

In response to the Supreme Court’s order, the Trump administration urged the justices in a filing Saturday evening to reject the ACLU’s request.

Solicitor General D. John Sauer wrote that the justices should leave it to the lower courts to first resolve the matter. The government, he said, has agreed not to remove detainees subject to the Alien Enemies Act. He also argued that those targeted for removal have received sufficient notice and time to contest their deportations.

Sauer said the court’s initial order “did not mandate any specific notice procedure.”

Sauer noted that the lower courts have not yet had a chance to rule on the relevant legal and factual questions. The Supreme Court “should not make those determinations in the first instance,” he wrote.

Some of the alleged gang members, he added, are subject to deportation under separate legal authorities not at issue before the Supreme Court.

Sauer asked that the justices “ensure that the government can continue conducting lawful and unchallenged removals” under that authority.

Following the Supreme Court’s emergency order, White House press secretary Karoline Leavitt maintained that the president was fulfilling a campaign promise.

“We are confident in the lawfulness of the Administration’s actions and in ultimately prevailing against an onslaught of meritless litigation brought by radical activists who care more about the rights of terrorist aliens than those of the American people,” Leavitt said in a statement.

Aziz Z. Huq, a constitutional law scholar at the University of Chicago, cautioned against reading too much into the interim order from the Supreme Court. The brief order does not address the underlying legal questions about Trump’s authority to use the wartime powers statute to deport alleged gang members.

In the case of Abrego García, the administration initially acknowledged his deportation was in error but has since dragged its feet, characterized Abrego García as a dangerous gang member and insisted it has no power to bring him back to the United States.

The fact that the Trump administration has taken such a hard-line position against correcting that error, Huq said, “may be working against them in this case.” He said at least some of the justices, in acting urgently overnight to pause any deportations, may have in the back of their minds that “the Trump administration has demonstrated when there are mistakes, they won’t correct them.”

The Alien Enemies Act has been invoked three times, all when Congress had declared war: during the War of 1812, World War I and World War II.

In a statement early Saturday, the ACLU’s lead counsel in the case, Lee Gelernt, said the organization was “relieved that the Supreme Court has not permitted the administration to whisk them away the way others were just last month.”

“The judges in law courts today, including the majority in the nation’s Highest Court, telegraph with these decisions that they have no understanding of law and its proper function and role,” he added.

On Sunday, Defense Secretary Pete Hegseth and Homeland Security Secretary Kristi L. Noem face a deadline to submit a report on conditions at the southern border, including their determination as to whether they recommend invoking the Insurrection Act to help obtain “complete operational control” of the border.

Trump declared an emergency at the southern border in January, which also gave Noem and Hegseth 90 days to submit their report. The Insurrection Act, a rarely used 19th-century law, would allow the president to deploy active-duty troops within the U.S. to enforce, in this case, immigration laws.

Cleve R. Wootson Jr. and Ben Brasch contributed to this report.