On Thursday, Trump administration officials admitted that Columbia student Mahmoud Khalil was arrested without a warrant. Khalil, a green card holder, has been detained since March, when Secretary of State Marco Rubio cancelled his visa over nebulous allegations of "pro-terrorist" speech.

Immigration authorities did not have a warrant for the arrest of Columbia activist Mahmoud Khalil, new court filing shows.

The Department of Homeland Security defended the warrantless arrest by saying it feared Mahmoud Khalil, a permanent resident, would flee.