A Donald Trump-appointed federal judge in Texas ruled that the president unlawfully invoked the Alien Enemies Act and blocked the administration from quickly deporting some alleged members of a Venezuelan gang.

Judge Rodriguez’s ruling is significant because it is the first formal permanent injunction against the administration using the AEA and contends the president is misusing the law.

The Alien Enemies Act has been used only three times in U.S. history, and all three instances came during officially declared wars.