How have ICE’s missions and structure evolved since inheriting functions from INS and the U.S. Customs Service?

Checked on January 27, 2026
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Executive summary

ICE was created in 2003 when the Homeland Security Act folded investigative and interior-enforcement functions of the Immigration and Naturalization Service and parts of the U.S. Customs Service into the new Department of Homeland Security, recasting immigration enforcement as a national-security task [1] [2]. Since then ICE has reshaped those inherited missions into a dual criminal-and-civil enforcement agency with a swollen budget, distinct directorates, and a far more visible—and polarized—role in U.S. immigration policy [2] [3] [4].

1. Birth from INS and Customs: an institutional remix aimed at security

The post‑9/11 reorganization dissolved INS and refitted investigative pieces of the old U.S. Customs Service into ICE, explicitly granting it a mix of civil and criminal authorities meant to protect national security and public safety—a deliberate reframing of immigration from administrative service to enforcement and counter‑terrorism work [1] [2] [5].

2. Mission architecture: two operational pillars and a legal arm

ICE consolidated its inherited responsibilities into three operational directorates—Homeland Security Investigations (HSI) for criminal probes, Enforcement and Removal Operations (ERO) for detention and deportation, and the Office of the Principal Legal Advisor (OPLA) for immigration litigation—supported by a management directorate, institutionalizing the split between criminal investigations and interior immigration enforcement [2] [3].

3. From offices to bureaus: renames, reorganizations and operational priorities

Leadership moves formalized the agency’s orientation: offices were rebranded (Office of Detention and Removal to ERO; Office of Investigations to HSI) to emphasize the two core missions—criminal investigations and civil removals—and policy shifts like Operation Endgame signaled an early appetite for broad interior enforcement goals [6] [5].

4. Scale-up: manpower, money and global footprint

ICE grew into a large law‑enforcement body with more than 20,000 personnel, hundreds of domestic and overseas offices, and an annual budget measured in billions—resources concentrated on HSI and ERO operations that vastly increased ICE’s presence compared with the patchwork enforcement of INS and Customs before 2003 [3] [7] [4].

5. Operational emphases and metrics: criminal targets, removals and detention

In practice ICE has emphasized criminal‑alien removals, transnational criminal investigations, and detention: DHS and ICE reporting cites hundreds of thousands of removals, large arrest tallies for transnational crime and gang enforcement, and millions of detention book‑ins in recent years—demonstrating a shift toward enforcement throughput as a principal performance metric [8] [9] [7].

6. Politics, public perception and competing narratives

The agency’s evolution made it a political lightning rod: critics portray ICE as increasingly militarized and punitive, calling for abolition after highly visible enforcement actions; defenders and ICE’s own materials frame the agency as protecting public safety and disrupting criminal and terrorist networks—an enduring tension documented in media and policy analyses [1] [5] [4].

7. Limits of current reporting and open questions

Available sources document the structural and mission shifts, budgets and activity metrics but do not uniformly resolve how internal culture, frontline discretion, or interagency dynamics (e.g., with CBP, which handles border patrolling) have evolved at the granular level; reporting shows CBP retains border patrol roles while ICE focuses interior enforcement, but deeper, systematic studies of decision‑making inside ICE are not supplied here [1].

Want to dive deeper?
How did Operation Endgame and early DHS deportation strategies reshape interior enforcement priorities in the 2000s?
What differences exist between Homeland Security Investigations (HSI) and Enforcement and Removal Operations (ERO) in case selection and outcomes?
How have ICE budgets, staffing levels, and detention practices changed across administrations since 2003?