What Does United States Immigration and Customs Enforcement (ICE) Do?

By Mark Debson · May 18, 2026 · 9 min read · Politics & World

A plain English guide to United States Immigration and Customs Enforcement. I cover what ICE actually does, how it is structured, how it differs from Border Patrol, and what your rights are.

Quick Answer

United States Immigration and Customs Enforcement, almost always shortened to ICE, is a federal law enforcement agency inside the Department of Homeland Security. It was created in 2003 after the post September 11 reorganisation of the federal government.

ICE is responsible for interior immigration enforcement, transnational criminal investigations, and the legal work of removing people from the country. It is organised into three main directorates: Homeland Security Investigations (HSI), Enforcement and Removal Operations (ERO), and the Office of the Principal Legal Advisor (OPLA).

ICE is distinct from Customs and Border Protection (CBP), which handles the physical border and ports of entry.

How ICE Was Formed

The agency is a child of the Homeland Security Act of 2002, which folded parts of the legacy U.S. Customs Service and the Immigration and Naturalization Service (INS) into a single body. The goal was to break down the wall between customs and immigration intelligence that investigators believed had contributed to the security failures around 9/11.

When ICE officially stood up in 2003, it inherited investigators, deportation officers, lawyers, and detention operations from multiple agencies, and was given an unusually broad mandate for a domestic law enforcement body.

The Three Core Divisions

Homeland Security Investigations (HSI)

HSI is the criminal investigative arm. Agents work cases in over 400 categories of federal crime, including:

• Human trafficking and human smuggling.
• Narcotics trafficking and weapons smuggling.
• Money laundering, bulk cash smuggling, and trade based financial crime.
• Cybercrime, child exploitation online, and intellectual property theft.
• Export control violations and sanctions enforcement.

HSI operates internationally through attaché offices in dozens of countries and partners regularly with foreign law enforcement and Interpol.

Enforcement and Removal Operations (ERO)

ERO is the directorate most people picture when they hear the word ICE. ERO officers identify, arrest, detain, and remove non citizens who are subject to removal under federal immigration law.

That includes people picked up after a criminal conviction, people who entered without inspection, people who overstayed a visa, and people whose immigration case has run its course in the immigration court system. ERO also manages the network of immigration detention facilities and the air operation that carries out removal flights.

Office of the Principal Legal Advisor (OPLA)

OPLA is the in house legal team. Its attorneys are the federal government's representatives in immigration court, opposite the non citizen's defence lawyer (when there is one) in front of a federal immigration judge inside the Executive Office for Immigration Review.

How ICE Differs From Border Patrol

This is the single most common point of confusion. ICE and Border Patrol are two different agencies inside the Department of Homeland Security.

• CBP (which includes Border Patrol and the officers at airports and land ports) controls who and what crosses the physical border.
• ICE investigates and enforces inside the country, after a person or shipment has already entered.

A person arrested at the Rio Grande by a Border Patrol agent is usually processed by CBP. If their case proceeds into the interior of the country, ICE typically takes custody.

Detention, Detainers, and Local Cooperation

ICE runs and contracts with a large network of detention facilities. Facility conditions, medical care, and oversight have all been the subject of recurring inspector general reports and litigation.

ICE also relies heavily on local law enforcement through two mechanisms. The first is the 287(g) program, which deputises selected state and local officers to perform certain immigration enforcement functions inside jails or in the field. The second is the detainer system, where ICE asks a local jail to hold a person up to 48 extra hours after they would otherwise be released, so ICE can take custody.

So called sanctuary jurisdictions limit one or both of these cooperation pathways. That is a political and legal choice that varies enormously by state and city.

Where the Public Debate Sits

ICE is one of the most politically charged agencies in the federal government. The debate generally splits along three axes:

1. Prioritisation. Should ICE focus its limited resources on serious criminal cases, or pursue civil immigration violations more broadly?
2. Detention. Should the United States detain people through their immigration proceedings, or release more of them on supervision and alternatives to detention?
3. Oversight. Should there be stronger independent oversight of ERO and HSI, particularly around use of force and conditions in custody?

Where the political needle sits on each of these tends to swing with the executive branch.

Knowing Your Rights

Anyone in the United States, regardless of immigration status, has certain constitutional rights in encounters with ICE officers.

• You have the right to remain silent. You do not have to answer questions about your immigration status.
• You have the right to refuse a search of your person or belongings without a judicial warrant.
• Officers cannot enter a private home without a judicial warrant signed by a judge or the consent of a resident. An administrative warrant signed by ICE alone is not a judicial warrant.
• You have the right to speak to a lawyer. In immigration proceedings the government does not appoint one, but a number of non profits provide free representation.

Frequently Asked Questions

Is ICE part of the police or the military?

Neither. ICE is a federal civilian law enforcement agency inside the Department of Homeland Security.

Can ICE arrest U.S. citizens?

ICE has no authority to remove a U.S. citizen, but HSI agents do investigate U.S. citizens involved in transnational crimes such as smuggling or financial crime.

How many people work for ICE?

ICE employs roughly 21,000 people across all directorates, support staff, and international postings.

The Bottom Line

United States Immigration and Customs Enforcement is more than the deportation work that dominates headlines. It is also the federal government's principal transnational crime investigator and the in court face of the United States in every immigration removal hearing. Understanding the three directorates, the line between ICE and CBP, and your own rights is the foundation for following any specific policy story about the agency.