Which immigration enforcement agencies existed before ICE and what were their functions?
Executive summary
The principal federal agencies that carried out immigration enforcement before the creation of U.S. Immigration and Customs Enforcement (ICE) in 2003 were the Immigration and Naturalization Service (INS) and the U.S. Customs Service, each with distinct legal homes and operational emphases: INS ran immigration admissions, naturalization, interior enforcement and operated the Border Patrol, while the U.S. Customs Service handled customs, trade and many border security functions tied to ports of entry [1] [2] [3].
1. The INS: America’s centralized immigration regulator and interior enforcer
For much of the 20th century the Immigration and Naturalization Service (INS), an agency within the Department of Justice, was the federal arm responsible for admitting immigrants, adjudicating naturalization, issuing immigration benefits, and enforcing immigration laws inside the United States, including interior arrests, removals and detention management; official histories and legal summaries identify INS as the predecessor to ICE for immigration enforcement functions [1] [3] [4].
2. The U.S. Customs Service: trade, ports of entry and border policing
The U.S. Customs Service, housed in the Treasury Department before 2003, focused on customs, tariffs, seizure of contraband, and policing the nation’s ports of entry; its investigative and border-facing authorities complemented INS’s migration duties and were folded into the post‑9/11 reorganization that created new DHS components [1] [5] [2].
3. The Border Patrol and blurred lines before DHS
The Border Patrol—historically operating under INS prior to the Homeland Security Act—carried out physical patrolling of the border and interdiction between ports of entry, but responsibilities and tactics often overlapped with both INS and Customs at ports and in enforcement operations, creating the practical duality that the 2003 reorganization sought to address [1] [6] [7].
4. Why the agencies were merged into DHS and ICE in 2003
After the September 11 attacks Congress enacted the Homeland Security Act of 2002, which dissolved INS and transferred many of its immigration enforcement and investigative functions and many Customs investigative elements into the newly created Department of Homeland Security, giving rise to ICE, CBP and USCIS—ICE inheriting primarily interior enforcement and investigative missions from INS and Customs [1] [5] [4].
5. Functional split that emerged: what ICE took on from its predecessors
ICE absorbed the investigative and interior enforcement elements of both the former U.S. Customs Service and the INS, consolidating homeland-security-focused investigations, interior arrests, removals, detention operations and legal representation for removals under a single DHS investigative agency while other functions (immigration services and border patrol at ports) landed in sister DHS agencies [2] [3] [4].
6. Competing narratives and implicit agendas in retelling the history
Official sources and government histories frame the reorganization as a security-driven efficiency measure after 9/11 [4] [5], while critics and civil‑liberties groups emphasize continuity of aggressive interior immigration enforcement across administrations and note that organizational change did not erase longstanding enforcement practices; contemporary reporting documents that roles between interior and border agencies have remained politically contested and operationally blurred since the merger [6] [7].
7. Bottom line for understanding “what existed before ICE”
The short answer: INS (in the Department of Justice) and the U.S. Customs Service (in the Treasury Department) were the principal predecessors whose investigative and interior enforcement arms were combined and reallocated into ICE, CBP and USCIS under the Homeland Security Act of 2002; the Border Patrol, long associated with INS, and Customs’ port functions were redistributed in that overhaul [1] [5] [2].