The Supreme Court handed President Donald Trump a massive win on Monday, voting 5-4 to allow his administration to continue rapidly deporting alleged gang members using the Alien Enemies Act.

The law, passed in 1798, gives presidents the authority to remove foreign nationals over the age of 14 from countries where the United States is either engaged in a declared war or subject to “invasion or predatory incursion” by their country of origin. The act has been invoked three times in U.S. history, each time during wartime, and is meant to counter the actions of foreign governments and regimes, not alleged criminals, gangs, or non-state actors. The law was also used to justify Japanese internment during WWII, and now, the Trump administration is using it to justify its deportations.

In an unsigned opinion, the Supreme Court tossed a district court decision that had temporarily blocked President Trump’s attempt to continue using the 227-year-old law after he sent almost 300 Venezuelan migrants to a notorious prison in El Salvador known for human rights abuses.

All nine justices agreed, however, that anyone the administration is seeking to deport under the Alien Enemies Act must receive notice of deportation and be given the opportunity to challenge the removal through “habeas petitions” — meaning that migrants have the right to have their detention or deportation reviewed by the federal court, but only for themselves and in the area where they are being detained.

The court’s three liberal justices dissented from the ruling, while Justice Amy Coney Barrett, who was appointed by Trump, partially dissented. Barrett joined Justice Sonia Sotomayor’s dissent calling the majority’s legal conclusion “suspect” and questioning if habeas claims should be the only way to contest deportations under the act.

“The Court’s legal conclusion is suspect,” wrote Sotomayor. “The Court intervenes anyway, granting the Government extraordinary relief and vacating the District Court’s order on that basis alone.”

CBS News 60 Minutes on Sunday released a report that found a majority of the Venezuelan migrants deported to prisons in El Salvador three weeks ago had no apparent criminal record or even criminal charges.

Earlier on Monday, the Supreme Court paused an order to bring back a Maryland man — who Trump’s Department of Homeland Security admitted was erroneously deported as a result of an “administrative error” — to the United States by midnight. Kilmar Abrego Garcia, who was arrested in front of his 5-year-old son, is one of potentially dozens of innocents currently trapped in the El Salvadoran mega-prison known for systemic torture and linked to unreported deaths and disappearances of inmates.

Following the court’s order, it remained unclear what will happen to the people who were already deported to El Salvador under the Alien Enemies Act.

In her dissent, Sotomayor argued that “funneling plaintiffs’ claims into individual habeas actions across the Nation risks exposing them to severe and irreparable harm.” She warned that “requirement may have life or death consequences.”

“Individuals who are unable to secure counsel, or who cannot timely appeal an adverse judgment rendered by a habeas court, face the prospect of removal directly into the perilous conditions of El Salvador’s CECOT, where detainees suffer egregious human rights abuses,” wrote the justice. “Anyone the Government mistakenly deports in its piecemeal and rushed implementation of the challenged Proclamation will face the same grave risks.”

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