On 9 March US immigration authorities unlawfully arrested and arbitrarily detained Mahmoud Khalil, a Palestinian activist and student organizer who recently graduated from Columbia University. He is a lawful permanent resident in the USA. Mahmoud was targeted for his role in student protests at Columbia University, where he was exercising his rights to freedom of expression and peacefully assembly. He has not been charged with a crime. He is being held in a detention center and authorities have informed him that they have “revoked” his permanent residency status and placed him in deportation proceedings. We demand authorities release Mahmoud immediately and respect his rights to freedom of expression, peaceful assembly and due process.