Between classes, when throngs of students stream into and out of Columbia University’s campus, the security lines can back up like a TSA checkpoint. There’s a switch-back path of metal fencing that leads into a white tent, where two sets of guards check and then swipe campus ID cards before letting students in and out.

The government is trying to deport Mahmoud Khalil, a permanent resident and defender of the Palestinian cause, accusing him of siding with terrorists.

The Trump administration says deportation can be a tool to combat antisemitism and terrorism. Critics see violations of free speech and immigrant rights.