A federal judge on Monday blocked the Trump administration from implementing a new rule that would ⁠limit how long foreign students and ⁠journalists can remain ​in the US without applying for extensions.

F Dennis Saylor, the US district judge in Boston, ruled in favor of a coalition of unions and higher education advocacy groups a day before ⁠the federal Department of Homeland Security (DHS)’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.

In a statement, James Percival, the DHS general counsel, criticized Saylor’s ruling, saying that ‌under it US Immigration and Customs Enforcement (ICE) must “permit this rampant abuse of our immigration system”.

“Come on a student visa, take one ‌class per semester, and stay here for decades,” he said.

Saylor, an appointee of George W Bush, wrote that the rule upended a system through which the United States for nearly five decades had issued visas to foreign students for their “duration of status”.

That system, he said, has permitted tens of millions of foreign students and researchers to come to the US, leading to “groundbreaking research in science, medicine, and technology, substantial economic growth, and a host of other benefits, often on a vast ‌scale”.

Saylor said the rule DHS adopted in July seeks to replace that system with one that would substantially restrict the overall number of foreign students, professors and journalists in the US.

Under the rule, F ​visas for international students and J visas that allow visitors on cultural exchange programs to work in the US would be capped at four years, while I visas for journalists, which now can last years, would be up to 240 days.

About 1.6 million people currently have F visas and another 500,000 have J visas. Major research universities like Massachusetts Institute of Technology (MIT) and Harvard have large percentages of foreign ⁠students, particularly at the graduate level, the judge noted.

If the rule took effect, such universities would probably suffer hundreds of millions of dollars ​in costs and enrollment would decline, Saylor said.

“The ​damage to the higher education system and to the economy of the United States is likely to ​be catastrophic,” Saylor wrote.

Miriam Feldblum, ‌the head of one ​of the plaintiffs, the Presidents’ ​Alliance on Higher Education and Immigration, said the judge’s ruling recognized the harm the rule would cause to international students, universities and the economy if it was allowed to take effect.

“While the case continues, this relief preserves the longstanding system that enables our colleges and universities – and our country – to attract, educate, and retain global talent,” Feldblum said.