A Timeline of Legal Battles Over Trump’s Use of the Alien Enemies Act

A complex and high-risk legal battle is playing out in federal courts over President Trump’s decision to use an 18th-century wartime law to deport Venezuelan migrants accused of gang membership.

In the latest development, a federal appeals court on Tuesday blocked Mr. Trump from using the powerful law, the Alien Enemies Act, to quickly deport the migrants. The court’s 2-1 ruling rejected the administration’s argument that they were part of an “invasion” of the United States by a foreign power.

The judges of the Fifth Circuit, considered one of the country’s most conservative appeals courts, said that their injunction applied only to the use of the Alien Enemies Act. They said it would not prevent the government from using other lawful means to remove foreign terrorists from the United States.

The case will now almost certainly head to the Supreme Court, where it would get a full hearing on the substantive question of whether Mr. Trump has used the act unlawfully. The Supreme Court has already issued orders limiting the government’s use of the law.

At times, the Trump administration has been accused of disregarding judicial orders as it proceeds with its immigration policies and deportation efforts. That has deepened legal scholars’ concern that the country could be facing a constitutional crisis.

Here’s a timeline of the legal battle:

March 14: The Trump administration issued an executive order invoking the Alien Enemies Act of 1798, a law that had last been used to justify the internment of Japanese, Italian and German immigrants during World War II. The proclamation said that the government was targeting the violent Venezuelan street gang Tren de Aragua, which was designated as a terrorist organization in February.
March 15: The American Civil Liberties Union filed a lawsuit in federal court in Washington seeking to block Mr. Trump from invoking the law. A federal judge in Washington, James E. Boasberg, was told by the A.C.L.U. that planes were leaving the United States with Venezuelans. He ordered the government not to deport anyone under the law and to return any planes that had already taken off.
March 16: President Nayib Bukele of El Salvador published a video on social media of men being led off a plane in handcuffs and taken into a prison in his country. Mr. Bukele posted an article about Judge Boasberg’s order and wrote, “Oopsie… Too late.” The Trump administration denied that it refused to comply with the order, and questioned the judge’s authority to issue it.
March 26: The U.S. Court of Appeals for the District of Columbia Circuit upheld Judge Boasberg’s block on the Alien Enemies Act in a 2-to-1 vote, denying an appeal by the Trump administration.

April 7: The Supreme Court said in an unsigned, three-page order that the Trump administration could continue to deport Venezuelan migrants, for the time being. It imposed constraints on the administration, saying that detainees must receive notice before they are deported and must be allowed to seek a hearing.
April 18: The A.C.L.U. filed suits and emergency petitions, saying that Venezuelans held at a detention facility in Texas had received removal notices. The notices, written in English, did not tell the Venezuelans how to contest their deportation, the A.C.L.U. said.
April 19: The Supreme Court issued an unsigned order blocking the Trump administration from deporting the Venezuelans held at the Texas facility “until further order of this court.” Two members of the Supreme Court’s six-justice conservative majority, Clarence Thomas and Samuel A. Alito Jr., dissented. The Venezuelans were returned to the facility, according to the A.C.L.U.
May 16: The Supreme Court sent the case back to the U.S. Court of Appeals for the Fifth Circuit, directing it to examine claims by the migrants that they could not be legally deported under the Alien Enemies Act. The court said that the Trump administration would not be able to deport the Venezuelan migrants until the appeals court ruled and the Supreme Court considered any appeal from that ruling.
June 30: The Court of Appeals for the Fifth Circuit began its hearing on the case. The Supreme Court had instructed the appellate judges to consider two issues: the substantive question of whether Mr. Trump’s use of the act was legal in the first place and a narrower one about how much — and what sort of — warning immigrants should be given before being expelled under the law.
Sept. 2: The federal appeals court issued a ruling blocking Mr. Trump from using the Alien Enemies Act to quickly deport the Venezuelan migrants. In a 2-1 ruling, the court said that it did not find that the act appliedto the migrants because there had been no “invasion or predatory incursion” by a foreign power.