What role do local law enforcement arrests and booking data play in generating ICE detainers and arrests?
Executive summary
Local arrests and booking records are often the raw material that triggers ICE interest: fingerprints and booking data flow into federal databases and can prompt ICE detainer requests that lead to transfers into immigration custody, though compliance by local jails is voluntary and varies by local policy and law [1] [2] [3]. The relationship is thus procedural and contingent—data and arrests enable ICE action, but local choices, deputization programs, and legal constraints determine whether that action becomes an arrest and detention [4] [5] [6].
1. Arrests and booking data as the ignition switch
When someone is arrested by local police, their biographical information and fingerprints commonly get entered into shared law enforcement systems; those records are visible to federal immigration authorities through initiatives that link local booking data to DHS databases, and ICE analysts use that information to identify removable noncitizens and prepare I-247 detainers or notices [1] [7]. ICE and allied programs describe detainers as a mechanism to pick up potentially removable individuals from a controlled environment, arguing the practice protects public safety by avoiding “at-large” arrests [2].
2. How a detainer becomes an ICE arrest: the transfer pathway
A detainer is formally a request that a jail hold somebody up to 48 hours beyond when they would otherwise be released so ICE can assume custody; when local agencies honor that request ICE officers can arrest and book the individual into the federal detention system, and those custody transfers are recorded in ICE’s Enforcement Integrated Database and related datasets [5] [7] [1]. Data compiled by researchers and FOIA-driven projects show many ICE detentions begin as transfers from local jails—TRAC and other datasets include case-level detainer records that document which agencies were asked to hold people [8] [1].
3. Local discretion and legal limits: not an automatic handoff
Despite the operational centrality of local bookings, compliance with ICE detainers is not mandatory: there is no federal law that compels local police or sheriffs to honor detainer requests, and jurisdictions with sanctuary policies often limit or condition cooperation, notify individuals of ICE requests, or refuse holds absent a warrant or judicial review [3] [5] [9]. Litigation and recent settlements have also pushed ICE to change practices in some regions, requiring neutral review before detainers can be issued and curbing unconstitutional holds in certain contexts [6].
4. Deputization and information-sharing magnify local impact
Programs that deputize local officers—most notably 287(g) agreements and jail enforcement models—expand the role of local arrests by authorizing local actors to query DHS systems, initiate immigration interviews, and even issue detainers themselves, blurring the line between local booking functions and federal immigration enforcement [4]. Critics note these programs increase the likelihood that routine arrests for low-level offenses will lead to immigration consequences; proponents frame them as essential tools to remove criminal aliens and enhance public safety [4] [2].
5. Data pipelines, transparency, and accountability problems
ICE’s detention statistics and research datasets come from administrative systems like the Enforcement Integrated Database and SSOR, which record detainer requests and subsequent detentions, but gaps and opaque practices have made outside oversight and accountability difficult—hence repeated FOIA efforts and third‑party compilations that aim to reconstruct how many detainers convert into actual ICE arrests [7] [8] [1]. Advocacy groups and defense counsel have documented systemic constitutional concerns—excessive holds, erroneous detainers, and lack of probable cause review—that complicate claims that data-driven detainer use is uniformly lawful [6] [3].
6. Competing narratives and incentives to cooperate
DHS and ICE present detainers as a safety-driven, pragmatic use of local custody to prevent dangerous persons from being released [2], while immigrant-rights organizations and many localities argue the practice undermines community policing and can turn routine arrests into deportation triggers, especially where financial incentives or intergovernmental contracts (IGSAs) create pressure to cooperate [5] [10]. The reality is mixed and heavily shaped by local policy choices, programmatic ties (like 287(g)), and litigation that has pushed both ICE and local agencies to alter behaviors in different jurisdictions [4] [6].