The deportation of a Palestinian Columbia student will be challenged in US federal court after the Trump administration's immigration policy sparked a legal battle. The student, Mahmoud Khalil, was arrested by Department of Homeland Security agents and his deportation was temporarily blocked by a US District Judge. The arrest has been denounced as an attack on free speech, and protests have taken place in New York City. Khalil's lawyers argue that his detention was illegal and retaliation for his role in protests at Columbia, which they say is protected political speech.