On Saturday night, agents of the Department of Homeland Security arrested and detained the Columbia University graduate Mahmoud Khalil. He is still in Ice custody in a remote Louisiana lockup known for extreme human rights violations, from denial of food and water to medical “care” verging on torture. Khalil, a Palestinian Syrian, emerged as a leader in Columbia’s Gaza solidarity encampment last year and a level-headed negotiator with university officials on behalf of the student protesters. Married to a US citizen, he holds a green card. Neither his American wife, who is eight months pregnant, nor his lawyers were warned...