A U.S. federal judge on Monday blocked U.S. President Donald Trump’s administration from implementing a new rule that would limit how long foreign students and journalists can remain in the U.S. without applying for extensions.

U.S. District Judge F. Dennis Saylor in Boston ruled in favour of a coalition of unions and higher education advocacy groups a day before the Department of Homeland Security’s rule was set to take effect.

Saylor said DHS adopted the policy based on “exceptionally weak” rationales. The agency had cited national security and the need to prevent fraud in the visa program, but the judge found it had not adhered to its legal obligations to engage with concerns about a policy change or consider less burdensome alternatives.