ICE is short for US Immigration and Customs Enforcement, a federal law-enforcement agency inside the Department of Homeland Security (DHS). In simple terms, ICE is responsible for enforcing certain immigration and customs-related laws, largely inside the United States rather than at the border, and for investigating crimes linked to the illegal movement of people, money and goods.
ICE was created in 2003 as part of the post-9/11 reorganisation of the US government. Congress passed the Homeland Security Act of 2002, which created DHS and reorganised functions that had previously sat in older agencies, including parts of the former Immigration and Naturalization Service and the US Customs Service.
For UK readers, it may help to think of ICE as closer to a combined “immigration enforcement and customs investigations” body than a single-purpose border force. It does not replace all US immigration agencies, and it does not do everything that gets described as “immigration”. The American system splits those responsibilities across multiple DHS components, each with different roles and powers.
ICE’s mission and the laws it enforces
ICE describes its mission as protecting the United States through criminal investigations and enforcing immigration laws to preserve national security and public safety.
A key point is that ICE operates using a mix of civil immigration enforcement and criminal investigations. In US law, many immigration matters are civil (for example, removal proceedings), while other conduct can trigger criminal offences (for example, certain forms of smuggling, trafficking, fraud, or illicit financial flows). The agency says it enforces and supports enforcement of hundreds of federal statutes connected to these areas.
The two main branches: ERO and HSI
ICE is best understood as two major operational arms with distinct jobs.
Enforcement and Removal Operations (ERO) is the part of ICE most people associate with arrests, detention and deportations. ICE says ERO manages “all aspects of the immigration enforcement process”, including identifying, arresting, detaining and removing people who are subject to removal under US immigration law.
Homeland Security Investigations (HSI) is ICE’s investigative arm, focused on complex criminal investigations. ICE says HSI investigates the illegal movement of people, goods, money, contraband, weapons and sensitive technology, working domestically and internationally with partner agencies.
This distinction matters because political debate often treats ICE as one single enforcement machine. In practice, ERO’s work is typically about immigration status and removals, while HSI’s work can resemble wider organised-crime and cross-border investigations, including offences that are not “immigration” in the everyday sense.
How ICE differs from Border Patrol, CBP and USCIS
ICE is frequently confused with the US Border Patrol. Border Patrol is part of US Customs and Border Protection (CBP), another DHS agency, and its core role is border security between official ports of entry. ICE, by contrast, is described in US government and congressional sources as primarily responsible for immigration enforcement in the interior of the United States, including worksite enforcement and overseeing immigration detention.
A third DHS component, US Citizenship and Immigration Services (USCIS), handles many administrative immigration functions such as processing applications and petitions. That is one reason why it is not accurate to treat “ICE” as the whole US immigration system.
What ICE actually does day to day
In practical terms, ICE activity typically falls into a handful of broad categories.
First, civil immigration enforcement. ERO identifies people who are removable under US law, makes arrests, manages detention and carries out removals. ICE also uses tools such as immigration detainers, which are requests to other law-enforcement agencies that already have someone in custody, asking to be notified and, in certain circumstances, to hold the person for a limited time so ICE can assume custody.
Second, detention management. ERO oversees detention arrangements and states it monitors conditions through compliance reviews intended to identify deficiencies and areas of concern at facilities holding detainees.
Third, criminal investigations. HSI conducts investigations into transnational and cross-border criminal activity, and ICE describes its work as targeting illegal flows of people and goods, as well as financial crime connected to these activities.
Fourth, legal representation in immigration court. ICE’s Office of the Principal Legal Advisor (OPLA) acts as the exclusive representative of DHS in removal proceedings before the immigration courts, which sit within the US Department of Justice’s Executive Office for Immigration Review rather than within DHS.
How ICE gets authority to arrest and detain
ICE’s powers come from federal statutes and regulations, mainly within Title 8 of the US Code, which covers “Aliens and Nationality”. While the detail is technical, congressional legal briefings emphasise that ICE’s statutory authorities for arrests and enforcement actions have remained broadly stable even as enforcement priorities change between administrations.
On detention, US law includes provisions governing arrest and detention pending a decision on removal, and rules governing detention after a removal order. These frameworks help explain why immigration detention can operate differently from criminal custody, even though detention often occurs in secure facilities.
Partnerships with local police and the 287(g) programme
One of the most debated parts of ICE’s operating model is the 287(g) programme, which allows state and local law-enforcement agencies to enter agreements with ICE so designated officers can perform certain immigration enforcement functions. ICE presents the programme as a way for local agencies to support enforcement of aspects of US immigration law under federal supervision.
Because the programme directly affects how local policing interacts with immigration enforcement, it attracts both strong support and strong criticism in the United States. For an evergreen understanding, the key point is that 287(g) is a formal mechanism by which ICE can expand operational capacity through partnerships rather than relying solely on federal officers.
Oversight, accountability and why ICE is controversial
ICE is routinely at the centre of political controversy in the United States, largely because its work involves coercive powers, detention, and decisions that affect families and communities. Disputes often focus on arrest tactics, detention conditions, cooperation with local agencies, and how priorities are set.
Internally, ICE has an Office of Professional Responsibility (OPR), which the agency says promotes organisational integrity through reviews and oversight of programmes and operations.
Externally, oversight also comes from the DHS Office of Inspector General, Congress and the courts. Inspector General reports have assessed how detention facilities are monitored and whether inspection regimes are effective, adding to the broader debate about detention standards and compliance.
For UK readers, the most important takeaway is that “ICE” is not one single policy choice. It is an institution with multiple branches, operating under federal law, and subject to political direction on priorities and resources. Understanding what the agency is designed to do, and which part of it does what, makes it easier to interpret breaking news and political claims without relying on slogans.
The bottom line
ICE is a DHS law-enforcement agency created in 2003. Its ERO branch is responsible for interior immigration enforcement, detention and removals, while its HSI branch runs criminal investigations into cross-border and transnational crime. ICE interacts heavily with other DHS agencies such as CBP and USCIS, and it uses legal tools, detention systems and partnership programmes such as 287(g) that can be contentious. The debate around ICE is often intense, but the basics are clear: ICE is a federal enforcement agency, not the whole US immigration system, and its work spans both civil immigration enforcement and criminal investigations.
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