On Friday afternoon, a federal immigration judge in Louisiana ruled that Mahmoud Khalil, the lawful permanent resident who was arrested last month for his advocacy for Palestinian rights at Columbia University, was removable – that is to say, deportable – under the law. Let’s be absolutely clear about how outrageous this decision is. The judge, Jamee Comans, had given the Trump administration a deadline to produce the evidence required to show that Khalil should be deported. In a functional state, such evidence would rise to a standard of extreme criminality necessitating deportation. But not in this case and certainly not...