The Trump administration wants to halt Harvard University from enrolling international students. Harvard on Friday sued the Trump administration for this, following which a federal judge blocked the administration from cutting off Harvard’s enrollment of foreign students.But the big question is: how can the federal govt dictate which students a private university can and cannot enrol?The govt has enormous power over who comes into the US, and who doesn’t. For college and universities, the Department of Homeland Security has a vast system just to manage and track the enrolment of the hundreds of thousands of international students studying across the country at any given time.But a school needs govt certification to use this database, known as SEVIS, for the Student and Exchange Visitor Information System. And this vulnerability is what the Trump administration is exploiting against Harvard.Homeland Security says, effective immediately, it has revoked a certification that allows Harvard to have access to SEVIS. Oddly enough, the students may still have valid visas. But Harvard is no longer able to log them into this all-important database.The announcement was a significant escalation in the administration’s efforts to pressure Harvard to fall in line with the president’s agenda.For each international student, Harvard inputs data into SEVIS to show that a student is enrolled full time, and thus meeting the terms of the visa that the student was issued.The system is overseen by US Immigration and Customs Enforcement, an arm of Homeland Security, which announced the termination Thursday.At Harvard, more than a quarter of its total student body, or 6,800 students, come from other countries.The SEVIS termination for Harvard would mean that all foreign students at the school would be in limbo. The students would, en masse, become deportable immediately, unless they transferred to another school, or unless a court intervened to block the termination by Homeland Security. Students who took no action to enrol elsewhere would be violating the terms of their status and subject to removal.After graduating, international students have 60 days from the end of their programme to leave the US or adjust their immigration status, by obtaining a job, for example.Students who are returning to university programmes typically can remain in the country during summer breaks because they are still enrolled for the coming term.But if SEVIS is terminated for Harvard, it’s unclear if students who would otherwise be returning would still be granted the summer grace period.The current spring term at Harvard ends Monday, according to the university’s calendar.It does not appear that Homeland Security revoked the student visas of Harvard’s international students. That means, in theory, they could leave or stay for the summer. They could go back to their home countries, potentially, and return to attend another school. Much of this is still unclear.