What historical agencies and statutes provided the legal authorities now exercised by ICE?

1. Institutional ancestors: INS, U.S. Customs Service and Treasury roots

The functions that ICE performs did not appear in 2003; they trace back to the U.S. Customs Service—rooted in Alexander Hamilton’s early Treasury-era statutes authorizing import taxes and customs enforcement—and to the Immigration and Naturalization Service, which handled interior immigration enforcement before DHS restructuring ^{[1] [2] [3]}. Historical responsibilities for collecting duties and policing cross‑border commerce evolved into criminal investigative work and immigration removal authority long before the modern agency’s birth ^{[1] [2]}.

2. Statutory bedrock: the Immigration and Nationality Act and federal criminal statutes

The INA, enacted in 1952 and codified as Title 8 of the U.S. Code, remains the primary statutory source granting authority to arrest, detain and remove non‑citizens—authority now exercised by ICE personnel under delegated executive power ^{[7] [8]}. Beyond the INA, HSI and ICE investigators draw on hundreds of other federal statutes—ranging from customs violations to money‑laundering and trafficking laws—that give the agency its unusually broad criminal jurisdiction ^{[6] [5]}.

3. Reorganization after 9/11: the Homeland Security Act and ICE’s creation

In the aftermath of the September 11 attacks, Congress consolidated disparate enforcement functions into the Department of Homeland Security; the Homeland Security Act of 2002 and the March 1, 2003 startup of DHS folded INS and the investigative portions of U.S. Customs into what became ICE, explicitly granting a blend of civil and criminal authorities intended to “better protect national security and public safety” ^{[2] [1] [4]}. That consolidation produced ICE’s dual structure—HSI for criminal investigations and ERO for detention and removal—reflecting the merger of investigative and interior enforcement missions from predecessor agencies ^{[4] [2]}.

4. Operational authorities and delegation: detainers, 287(g), and intergovernmental cooperation

Specific operational tools used by ICE today—such as detainers, the 287(g) program deputizing local officers, and formal MOAs with state and local agencies—are statutory or regulatory descendants of INA provisions and implementing regulations; courts and commentators have contested how those tools are used, especially the voluntary vs. mandatory nature of local compliance with detainers under 8 C.F.R. § 287.7 ^{[7] [6] [8]}. HSI agents carry statutory authority to enforce Title 8 and numerous other laws, while ERO executes removal and detention authorities delegated through immigration statutes and DHS policy ^{[6] [2]}.

5. Contested legacy: policy, civil‑rights challenges and political agendas

The same legal patchwork that gives ICE expansive reach has produced intense controversy: critics argue the agency’s post‑2003 configuration amplifies enforcement priorities at the expense of due process and community trust, and organizations and media have documented workplace raids, family separations and conditions in detention as flashpoints for calls to reform or abolish ICE ^{[9] [10]}. Legal pushback—especially in litigation over detainers and state‑local cooperation—highlights that statutory authority is interpreted through courts, policy choices and political priorities, and that advocates on different sides of the debate bring distinct agendas when they invoke ICE’s legal lineage ^{[7] [11]}.

Conclusion

ICE’s current authorities are an accretion: rooted in early customs law and Treasury functions, codified in the INA and other mid‑century statutes, expanded into criminal enforcement through a broad portfolio of federal laws, and consolidated into a single DHS component after 9/11 by the Homeland Security Act—producing an agency that wields both civil immigration powers and broad criminal investigative jurisdiction, while remaining the focus of legal and political contestation ^{[1] [7] [4] [2]}.