Trump Administration Live Updates: Trump Says He Will Discuss Ukraine With Putin on Tuesday

“Oopsie … Too late,” Mr. Bukele wrote in a social media post on Sunday morning that was recirculated by the White House communications director, Steven Cheung.

Around the same time, Secretary of State Marco Rubio, in another social media post, thanked Mr. Bukele for a lengthy post detailing the migrants’ incarceration.

“This sure looks like contempt of court to me,” said David Super, a law professor at Georgetown University. “You can turn around a plane if you want to.”

Some details of the government’s actions remained unclear, including the exact time the planes landed. In a Sunday afternoon filing, the Trump administration said the State Department and Homeland Security Department were “promptly notified” of the judge’s written order when it was posted to the electronic docket at 7:26 p.m. Eastern time on Saturday. The filing implied that the government had a different legal authority for deporting the Venezuelans besides the one blocked by the judge, which could provide a basis for them to remain in El Salvador while the order is appealed.

The administration said that the five plaintiffs who filed suit to block their deportations — the suit that yielded the judge’s order — had not been deported.

On Sunday, legal analysts were still stitching together the timeline, trying to determine where the planes were shortly before 7 p.m. Eastern time on Saturday — and how close the Trump administration is to open defiance of the Constitution’s system of checks and balances.

That was when Judge James E. Boasberg of the U.S. District Court for the District of Columbia ordered the Trump administration to cease its use of an obscure wartime law, the Alien Enemies Act of 1798, as a pretext for the expulsion of migrants, and immediately return anyone it was expelling under the act to the United States.

Regardless of the timing, Judge Boasberg’s order appeared to have been brushed aside by the Trump administration, which went ahead and turned the Venezuelans over to the government of El Salvador for detention. In touting the event, Mr. Rubio made no mention of Judge Boasberg’s order. On Saturday, the judge had ordered the government to return anyone removed under the Alien Enemies Act to U.S. soil, “however that’s accomplished — whether turning around the plane or not.”

The White House press secretary, Karoline Leavitt, issued a statement on Sunday denying that the administration had refused to comply with the order, and questioning the judge’s authority to issue it.

In a 25-page appellate filing on Sunday, Justice Department lawyers called the order by Judge Boasberg, who was nominated to the bench by President Barack Obama, a “massive, unauthorized imposition on the Executive’s authority.” Mr. Trump’s actions, they argued, “are not subject to judicial review” because of what they said was the presidency’s inherent constitutional authority over national security and foreign policy matters, and that the federal courts as a whole lacked jurisdiction over his exercise of a “war power.”

Federal judges have been clashing with the Trump administration for weeks over dozens of executive actions that the courts have tried to put on temporary hold while their legality is assessed. In some cases, plaintiffs who sued the administration and won obtained favorable judicial orders have returned to court saying the administration was failing to comply with them.

On Friday, a kidney transplant specialist and professor at Brown University’s medical school was deported from the United States, even though a court had ordered her expulsion temporarily blocked, according to her attorney and federal court documents.

But the mockery by Mr. Bukele — and the tacit endorsements of it by senior administration officials — seemed to push Washington closer to a constitutional crisis, critics of the administration said Sunday.

“Court order defied,” wrote Mark S. Zaid, a Washington lawyer whose legal fights with the administration have put him in Mr. Trump’s cross hairs. In a social media post, Mr. Zaid said the events on Saturday and Sunday were the “start of true constitutional crisis.”

Other experts were concerned but more cautious.

“We need a little more development of the facts,” said Adam Winkler, a professor at the University of California, Los Angeles. “If the report is true about timing, then it does seem like the administration has ignored a binding court order. And if that’s the case, then the courts must act swiftly to punish the Trump administration. We cannot have the executive branch ignoring the orders of the judicial branch.”

On Saturday, the Trump administration claimed authority under the Alien Enemies Act to immediately deport any Venezuelan citizen age 14 or older who the administration says is a member of Tren de Aragua, a violent criminal gang that was designated a foreign terrorist organization in February. In its proclamation on Saturday, the White House called the gang a “hybrid criminal state” that was “perpetrating an invasion” of the United States, justifying use of the 1798 law, which had only been invoked three times before — for the War of 1812, World War I and World War II.

Earlier in the day, anticipating that step, five Venezuelans in federal custody filed a class-action lawsuit claiming that their expulsion on that basis would violate federal law and the Constitution’s guarantee to due process. Judge Boasberg soon issued a restraining order blocking their removal.

Then, in a hearing on Saturday afternoon, lawyers for the plaintiffs told the judge that two planes carrying other Venezuelans expelled under the Alien Enemies Act were “in the air.” From the bench, shortly before 7 p.m., Judge Boasberg ordered the government to turn the planes around and bring the detainees back. Then he issued a second written order barring the government from using the Alien Enemies Act to deport any suspected members of Tren De Aragua.

The flights to El Salvador marked the second time in quick succession that the administration has been accused of deporting someone in violation of a court order. Lawyers for Dr. Rasha Alawieh, a doctor specializing in kidney transplant patients and a professor at Brown University’s medical school, said she was deported on Friday despite a court order to the contrary from Judge Leo T. Sorokin of the Federal District Court in Massachusetts. On Sunday, Judge Sorokin gave the government a Monday deadline to respond to charges that it had “willfully disobeyed” his order.

Skye Perryman, chief executive of Democracy Forward, which has helped bring a multitude of lawsuits against the Trump administration, said she still expects the government to comply with court orders.

“We will continue to work through the courts to ensure that orders are faithfully executed and — if not — that there is accountability for the government,” she said in a statement on Sunday.

The White House press secretary, Karoline Leavitt, said on Friday that court orders blocking Mr. Trump’s agenda were “unconstitutional and unfair.” That added to speculation, prompted by statements made by Mr. Trump and Vice President JD Vance on social media, that the White House might openly defy the judiciary, which under the Constitution is a branch of government equal in authority to the executive.

Mr. Super, the Georgetown law professor, said the Justice Department’s arguments for deference to the president’s sole power to conduct foreign policy may be weighed by an appeals court when it considers whether to uphold Judge Boasberg’s order, but they do not provide a justification for violating the order.

“You have to comply with court orders until they’re reversed,” he said. “Otherwise, you and I become our own courts. We follow what we think is right, we violate what we think is wrong, and the judges may as well go home.”

Tim Balk, Alan Feuer, Charlie Savage, Maggie Haberman, Devlin Barrett, Annie Correal and Dana Goldstein contributed reporting. Seamus Hughes contributed research.