The Trump administration’s detention of a green-card holder who was a leader in the Columbia University protests against Israel has put a face on the debate over immigration and the limits of free speech, with a sympathetic twist: The man, Mahmoud Khalil, is married to an American, and they are expecting their first child next month.

If the Trump Administration comes out on the wrong side of this fight, it will be because defending free speech remains a politically lucid and powerful principle.

A DHS official defended Khalil’s detention in an interview on Thursday but did not provide additional details for his arrest.