In the weeks after September 11, the Justice Department detained more than 1,200 noncitizens — overwhelmingly Muslim men from South Asia and the Middle East — on immigration violations, material-witness warrants, and no charge at all, holding many under a blanket "hold until cleared" policy while the FBI worked through its leads. Names were kept secret, hearings closed, and at Brooklyn's Metropolitan Detention Center detainees were slammed into walls, kept in twenty-three-hour lockdown under constant lighting, and denied counsel for weeks.
The Justice Department's own Inspector General documented the abuse in a scathing 2003 report and confirmed the central fact: none of the sweep's detainees was convicted of a terrorism offense connected to the attacks. The episode — mass preventive detention organized by nationality and faith — set the war on terror's domestic template, and the Supreme Court later closed the courthouse door on the survivors, holding in Ziglar v. Abbasi (2017) that the officials who designed the policy could not be sued.