Immigration Detention Primer

ICE Detention System

The U.S. Immigration and Customs Enforcement (ICE) detention system depends on hundreds of jails, prisons, and other facilities largely owned as well as run by others—some by local government agencies and others by private, for-profit companies. The vast majority of these detention facilities are either owned or are operated by for-profit corporations. Using beds in these facilities that are widely scattered across the country, ICE manages a large complex system with daily flows of individuals both into as well as out of ICE custody. In addition, an even larger number of individuals already in ICE custody are continuously being transferred among these facilities.

While many of these detention facilities are concentrated along the southwest border with Mexico, every state and territory—including Puerto Rico, Guam, the Virgin Islands, and the Northern Mariana Islands—has at least one ICE detention facility. Some detention facilities are temporary holding rooms, while others are designed for long-term stays. Some hold only a single person on one occasion during the entire year, while others have tens of thousands who pass through their doors during this same period. A few are designated to hold families. Custody of unaccompanied juveniles is handled by a separate agency, the Office of Refugee Resettlement (ORR) in the Department of Health & Human Services.

The principal reason individuals leave ICE detention is when they are deported. The next largest group are individuals and families released on bond or on their personal recognizance while their cases are pending. Others are released—frequently after long detention periods—because their cases have concluded and they were found to have a lawful right to remain in the country. TRAC uses the Freedom of Information Act (ICE) to make monthly request for detailed ICE anonymized records on each person it has detained. TRAC analyzes this data and publishing both reports and online tools to allow the public to see the characteristics of who are being detained, where they are being detained, and how long they have been detained.

ICE Alternatives to Detention Programs

The Enforcement and Removals Operation (ERO) within Immigration and Customs Enforcement (ICE) is responsible for managing detention as well as individuals and families released from ICE detention into the interior of the United States while their cases are pending or removal is deferred for other reasons. ICE refers to this group of now over three million persons as their "non-detained docket." A relatively small number out of those on ICE's non-detained docket are assigned to one of several "alternatives to detention" (ATD) programs for closer monitoring. This is achieved through the use of technology or more frequent check-ins with ICE. The remainder not assigned to an ATD program on this non-detained docket may—at ICE's discretion—only be required to check in with ICE once or so a year.

Initial use of ATD by ICE began in FY 2004, and the technologies used have evolved over time. See Congressional Research Service July 2019 report for additional history and details. Currently, the main technologies include the use of ankle bracelets that employ GPS location monitoring, smart phone applications (SmartLINK) that utilize both facial recognition and GPS location monitoring, and telephonic reporting using frequent telephone check-ins (TR or voiceID). Once assigned to an ATD program, people on average remain under ATD monitoring for several years.

Responsibility for managing individuals assigned to ATD programs is divided among ICE ERO field offices that divide the country into areas of responsibility, commonly referred to as AORs.

TRAC uses the Freedom of Information Act (ICE) to make monthly request for detailed ICE anonymized records on each person in custody or assigned to an ATD program, as well as others on the non-detained docket. ICE has yet to furnish any specific details on those assigned to an ATD program so only more limited aggregate statistics are now available. TRAC's aim in requesting these data is to be able publish both reports and online tools to allow the public to see better understand the full dimensions of these programs, including the characteristics of who is being placed on ATD programs and how long they remain, which programs are being used, each program's effectiveness, and how use varies geographically.