A federal judge has issued a preliminary injunction blocking the Trump administration’s attempt to deport Mahmoud Khalil, an anti-Israel activist detained on foreign policy grounds. The ruling, handed down by U.S. District Judge Michael Farbiarz, calls into question the legality of the Trump administration’s use of a 1952 immigration law to justify Khalil’s detention. The decision has significant implications for how the U.S. handles cases involving individuals whose presence is claimed to jeopardize foreign policy interests.