Donald Trump campaigned on the promise that he would crack down against pro-Palestinian student protesters. Over the past few weeks, he has forcefully followed through. His administration has directed investigators at Immigration and Customs Enforcement (Ice), who would typically target human traffickers and drug smugglers, to track down students who may have shown sympathy for the Palestinian cause in social media posts. His secretary of state has deployed an obscure statute to detain PhD candidates and researchers. Openly flouting bedrock principles of free speech in the US, his administration has thrown the weight of its executive power into crushing political...