The Supreme Court announced Friday that it would keep in place a temporary block on deportations of Venezuelan migrants accused of being members of a violent gang and threatened with removal from the country under a rarely invoked wartime law.

The justices sent the case back to a federal appeals court, directing it to examine claims by the migrants that they could not be legally deported under the Alien Enemies Act, the centuries-old law invoked by the Trump administration. The justices said the appeals court should also examine what kind of notice the government be required to provide that would allow migrants the opportunity to challenge their deportations.

The court said its order would remain in place until the 5th U.S. Circuit Court of Appeals ruled and the Supreme Court considered any appeal from that ruling.

Justice Samuel Alito wrote a dissent. He was joined by Justice Clarence Thomas.

The Trump administration has attempted to use the law as a tool in its signature initiative to speed the deportation of millions of migrants, leading to a clash with a skeptical judiciary.

The Supreme Court has already weighed in on the issue once, agreeing in early April to temporarily allow the administration to proceed with its use of the law, provided it gave migrants subject to it the opportunity to challenge their deportations in court.

As those challenges have been filed, several lower court judges have concluded that the administration has exceeded the scope of the law, which can be invoked only when the United States has been subject to “invasion” or “predatory incursion,” and have blocked the deportation of groups of Venezuelans.

Friday’s order came after a high-stakes legal fight between the Trump administration and lawyers from the American Civil Liberties Union in one of those challenges. The lawyers rushed to the court April 18 after getting word that Venezuelan migrants detained in Texas and accused of being members of Tren de Aragua, a Venezuelan gang, had received notices of imminent removal and were being loaded on buses, presumably to be taken to the airport.

The group quickly filed a lawsuit in a federal trial court in Abilene, Texas, on behalf of two of the Venezuelans held at the detention center. Justice Department lawyers responded, telling a trial court judge that they had no immediate plans to deport the detainees.

The judge, James W. Hendrix, who was appointed during the first Trump administration, declined to issue an order temporarily blocking the deportations.

The ACLU subsequently asked the Supreme Court to act instead.

After midnight April 19, the justices temporarily paused the deportations, writing, “The government is directed not to remove any member of the putative class of detainees from the United States until further order of this court.”

The justices moved swiftly that night, and the emergency application has been pending before the court since.