Detained illegal immigrants are generally held in custody until an Attorney General decides whether or not the person should be removed from the United States, explains Cornell University Law School. In some cases, the illegal alien may be eligible for bond, but the bond can be revoked at any time.
Each case is handled individually, so some detainees may be allowed to remain in the United States for a specific amount of time to receive proper documentation, according to Cornell University Law School. If the Attorney General orders a removal, the removal order is reviewed by the court, and a removal date is established. The removal date usually falls within 90 days of the court's final decision.