Mahmoud Khalil isn’t an illegal alien. He isn’t a terrorist. He’s a Columbia graduate student and a legal U.S. resident. He's a husband. And his wife, a US Citizen—8 months pregnant—has no idea where he is. The Department of Homeland Security snatched him off campus, disappeared him without a trace. No charges. No trial. Just gone. This is how authoritarian regimes operate. It's what happens when the First Amendment only applies to the “right” kind of people—it's only a trial balloon for a broader crackdown on speech. If they can do it to Khalil, they can do it to you. First, they come for the speech of legal immigrants. If we don't speak up, do you know what comes next?