6 The report addresses nine basic questions at the core of immigration detention: 1. Who is detained? 2. What is the detention system? 3. What legal frameworks govern detention? 4. How do politics shape detention? 5. How long are migrants detained? 6. What are the conditions for migrants in detention? 7. What is “de facto” detention? 8. How do migrants challenge detention? 9. What alternative approaches exist to replace detention? In answering these questions, the report contrasts laws and policies with the firsthand experiences of detained individuals, highlighting the shortcomings of legal frameworks. It also sheds light on the diverse factors influencing detention across different contexts, and it identifies patterns that underscore the need to adopt more humane practices. By exploring these core questions, the report aims to foster a global understanding of immigration detention, and ultimately advocates for its elimination. Immigration Detention Across Borders Detention of Asylum Seekers in the United States and the European Union