What role do DHS, ICE, and local law enforcement databases play in measuring immigrant crime rates?
Executive summary
DHS serves as the central aggregator and public publisher of immigration enforcement statistics while ICE is the operational collector of arrests, detentions and removals that feed those statistics; local law-enforcement databases are often the primary source of arrest records that trigger immigration actions and therefore shape measured “immigrant crime” signals [1] [2] [3]. These systems produce useful raw counts but are shaped by agency missions, data definitions, and local cooperation rules—factors that complicate simple claims about immigrant crime rates [4] [5].
1. DHS: the central publisher and definitional arbiter
The Department of Homeland Security gathers, standardizes, and publishes monthly and annual enforcement tables that researchers and journalists use as the official statistical record for immigration enforcement—covering encounters, arrests, book-ins/book-outs, detentions, removals, returns and other metrics [6] [1]. That role makes DHS the arbiter of definitions (what counts as an “administrative” versus “criminal” arrest, for example) and the public face of enforcement data, meaning methodological choices at DHS directly shape headline figures cited in debates [4].
2. ICE: the operational data generator and enforcement actor
ICE’s Enforcement and Removal Operations collects person-level encounter and arrest data—ICE reports arrests, detentions, removals and criminal vs administrative case counts—which become core inputs for measures of “criminal aliens” and enforcement volume [6] [7]. ICE’s institutional mission to prioritize removal of individuals with alleged criminal histories also influences which encounters are elevated and reported as “criminal,” a framing emphasized in DHS and ICE public statements [2] [8].
3. Local law enforcement databases: the frontline inputs and gatekeepers
Local police and sheriff databases supply the conviction and arrest histories that DHS, CBP, and ICE check when processing encounters; CBP explicitly notes that records checks of available law‑enforcement databases reveal conviction histories used in its “criminal alien” tallies [3]. But state and local policies governing cooperation—ranging from broad collaboration to strict non‑cooperation or reporting requirements—mean the pipeline of local records into federal immigration datasets varies widely and shapes apparent arrest and remand patterns [5].
4. How measurements can mislead: arrests, convictions, duplicates and time bases
Government counts frequently report arrests or ICE encounters rather than convictions, and multiple datasets may count the same person more than once across agencies and time periods; researchers warn there is no single “master” spreadsheet and that serious research requires merging DHS, TRAC, FBI and local data while accounting for duplicate counts and differing time bases [9]. Independent analyses and watchdog groups have shown many in ICE custody lack criminal convictions and that headline arrest totals therefore do not equal proof of elevated criminality among immigrants [10] [11].
5. Incentives, framing and competing narratives
DHS and ICE emphasize public‑safety narratives—e.g., highlighting “criminal illegal aliens” and proportions of ICE arrests tied to criminal charges—to justify enforcement actions, a framing visible in DHS press claims [8] [2]. Countervailing reporting from advocacy groups and investigative outlets documents detention growth, oversight gaps, and high numbers held without convictions, which suggests agency-reported statistics also serve political and operational agendas that must be read alongside the numbers [12] [11] [10].
6. Practical implications for measuring immigrant crime rates
Reliable measures require linking arrest records to adjudicated outcomes, deduplicating cross‑agency encounters, adjusting for local cooperation policies, and comparing rates to appropriate denominators (resident population, not encounters), yet the available DHS/ICE/local feeds do not by themselves deliver that cleaned, comparable rate without substantial analytic work [9] [6]. Where local jurisdictions restrict ICE access, fewer federal arrests can reflect policy choices rather than underlying crime differences, so raw ICE tallies alone are a poor proxy for true comparative crime rates [5] [7].
7. Bottom line
DHS and ICE databases are indispensable for tracking enforcement activity and identifying individuals encountered by federal immigration authorities, while local law‑enforcement systems provide the criminal-history inputs; however, mission-driven definitions, data fragmentation, duplicate counting, and local policy variation mean these databases measure enforcement activity more reliably than they measure true immigrant crime rates without additional linkage, cleaning, and contextual analysis [1] [6] [9].