5/7/19 A federal district court prevented USCIS from imposing a new policy that radically changed how the agency determines when a foreign student or exchange visitor is “unlawfully present” in the US. “Unlawful presence” is a legal term used to describe any time spent in the US after a foreign national’s period of authorized stay has ended. …under USCIS’ final policy memorandum, far more international students and employees (such as teachers in the US as exchange visitors) would be subject to 3- and 10-year bars on future admissibility.