A federal judge in Boston has temporarily blocked the Trump administration from enforcing new limits on how long foreign students, exchange visitors and journalists may remain in the United States. U.S. District Judge F. Dennis Saylor issued the ruling Monday, one day before the Department of Homeland Security rule was scheduled to take effect. The case was brought by a coalition of unions and higher-education advocacy organizations, including the Presidents’ Alliance on Higher Education and Immigration. The rule, adopted by DHS in July, would have replaced the longstanding “duration of status” system with fixed time limits. F visas for international students and J visas for cultural-exchange participants would have been capped at four years. I visas for foreign journalists would have been limited to 240 days, even though those visas can currently remain valid for years. The government defended the changes by citing national security and the need to reduce fraud in visa programs. But Saylor said DHS relied on “exceptionally weak” justifications and failed to adequately address public concerns or consider less burdensome alternatives. The judge also found that the policy could cause severe damage to colleges and the broader economy. About 1.6 million people currently hold F visas, while roughly 500,000 hold J visas. Research universities, including Harvard University and the Massachusetts Institute of Technology, rely heavily on international students, particularly in graduate programs. If enforced, the rule would likely have caused enrollment declines and hundreds of millions of dollars in costs for higher-education institutions, Saylor wrote. He warned that the effects on the nation’s universities and economy could be “catastrophic.” Saylor, who was appointed by President George W. Bush, said the existing system has enabled tens of millions of students and researchers to study and work in the United States over nearly five decades. Their contributions, he wrote, have supported advances in science, medicine and technology as well as significant economic growth. DHS General Counsel James Percival criticized the decision, arguing that it would require U.S. Immigration and Customs Enforcement to tolerate abuse of the immigration system. He pointed to cases in which people might enroll in minimal coursework while remaining in the country for many years. Miriam Feldblum, executive director of the Presidents’ Alliance, said the order protects international students, universities and the national economy while the lawsuit continues. The ruling leaves the current visa framework in place for now, but the broader legal challenge has not been resolved.