This report offers the most comprehensive study yet of Assam’s citizenship determination system, comprising 100 Foreigners Tribunals (FTs), the National Register of Citizens (NRC), and border policing mechanisms. These bodies decide who is recognised as an Indian citizen and who is labelled a “foreigner,” with profound consequences for those targeted. Drawing on almost 1,200 High Court cases and landmark Supreme Court rulings, along with extensive fieldwork and interviews with defence lawyers and affected individuals, it examines how these institutions operate, the laws they apply, and their compliance with constitutional and international human rights standards. The findings reveal routine rejection of valid evidence and an absence of procedural safeguards. Over 165,000 people have been declared “foreigners,” 85,000 cases remain pending, and more than 1 million NRC appeals may soon follow—an institutionalised machinery of exclusion disproportionately harming marginalised communities and risking replication elsewhere in India.