A judge appointed by Donald Trump in Texas has, for the first time, ruled that the president’s use of the Alien Enemies Act (AEA) to expedite the deportation of Venezuelan migrants with minimal due process “is unlawful.” The judge has prohibited the administration from deporting more individuals under this 18th-century wartime authority in his district.

Although many colleagues have clearly questioned the constitutionality of Trump’s application of the AEA, U.S. District Judge Fernando Rodriguez became the first federal judge to rule that Trump’s March 15 proclamation overstepped “the scope of the statute” and conflicted with “the plain, ordinary meaning of the statute’s terms.”

“As a result, the Court concludes that as a matter of law, the Executive Branch cannot rely on the AEA, based on the Proclamation, to detain the Named Petitioners and the certified class, or to remove them from the country,” Rodriguez wrote in the 36-page opinion.

Trump is the first president since World War II to invoke the AEA, which authorizes him to summarily remove “natives, citizens, denizens, or subjects” of a “hostile nation or government” when there is “declared war” against it or when it has “perpetrated, attempted, or threatened against the territory of the United States” an “invasion or predatory incursion.” In a controversial and novel use of the power, Trump declared that the Venezuelan gang Tren de Aragua (TdA) had engaged in an “invasion” or “predatory incursion” of the U.S. such that any member of the group was summarily removable under the Act.

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The administration asserted that the gang constituted a “hybrid criminal state” for purposes of invoking the AEA.

Rodriguez rejected the administration’s interpretation of the statute, reasoning that the president did not provide any evidence that would enable the court to determine whether the alleged conduct “satisfies the conditions that support the invocation of the statute.” The judge cited an appellate case in which the court held that a “state of invasion” does not exist simply because a government official “has uttered certain magic words” before concluding that the defendants “do not possess the lawful authority” to conduct removals under the AEA.

“The President cannot summarily declare that a foreign nation or government has threatened or perpetrated an invasion or predatory incursion of the United States, followed by the identification of the alien enemies subject to detention or removal,” Rodriguez wrote. “Allowing the President to unilaterally define the conditions when he may invoke the AEA, and then summarily declare that those conditions exist, would remove all limitations to the Executive Branch’s authority under the AEA, and would strip the courts of their traditional role of interpreting Congressional statutes to determine whether a government official has exceeded the statute’s scope. The law does not support such a position.”

The administration controversially used the AEA on March 15 to transport 137 Venezuelan migrants to CECOT, a notorious work prison in El Salvador, despite a federal judge in Washington ordering those flights and detainees to return to the country. Though the case was later dismissed from Washington for jurisdictional issues, that judge found probable cause to hold the Trump administration in criminal contempt for flouting his order. Contempt proceedings are still ongoing before U.S. District Judge James Boasberg.

Since then, federal judges in New York, California, Colorado, and Massachusetts have issued court orders prohibiting removals under the statute, primarily over concerns about the process depriving individuals of due process. The Supreme Court has also stopped removals under the AEA without discussing the merits of the case.

“The importance of this ruling cannot be overstated,” Lee Gelernt, an attorney with the American Civil Liberties Union (ACLU) who represented the defendants in the case said in a statement. “This is the first court to squarely rule on the fundamental question of whether a wartime authority can be used during peacetime and properly concluded it can not.”