How have state and local non-cooperation policies statistically affected ICE arrest and detention rates?
Executive summary
State and local non-cooperation—commonly called “sanctuary” or restriction policies—have a measurable, if uneven, dampening effect on ICE’s ability to convert local arrests into federal immigration arrests and detention admissions, lowering per-capita ICE arrest rates in jurisdictions that limit transfers and detainers but not eliminating interior enforcement because ICE adapts tactics (court, workplace, at-large arrests) and relies on cooperative states and facilities to meet detention needs [1] [2] [3] [4]. Observational datasets and advocacy analyses show clear statistical contrasts between high-cooperation states with elevated ICE arrest rates and low-cooperation jurisdictions with suppressed jail-based referrals, while federal data and DHS statements highlight countervailing trends and operational workarounds that complicate any simple causal claim [5] [6] [7].
1. How the numbers line up: cooperative states show higher ICE arrest and detention flow
Multiple independent analyses find that states and localities that formally authorize cooperation—through deputization programs, 287(g)-style arrangements, or routine acceptance of ICE detainers—report substantially higher rates of ICE arrests and transfers from jails into detention; Prison Policy’s analysis shows states such as Florida, Texas, Louisiana and Georgia producing “high numbers of arrests” tied to mandated cooperation [1], and Honolulu Civil Beat cites that arrest rates were higher in states that fully cooperated with federal goals [8]. National statistics and compilations also show that ICE relies on transfers from local jails as a major source of people booked into detention—ICE and TRAC data report large shares of detention intakes originating from ICE arrests and local law enforcement handoffs, which swell detention populations in cooperative regions [5] [7].
2. Sanctuary laws blunt jail-to-ICE pipelines and lower per-capita arrest rates
Regions that legally restrict transfers and detainer practices—California’s sanctuary statutes and similar policies in New York, Illinois and Oregon—consistently register lower per-capita ICE arrest rates and fewer jail-origin detentions, as researchers attribute Northern California’s nation-low arrest rate to state limits on local cooperation and community resistance [2]. Prison Policy’s national comparison likewise finds that limiting access to jails and public buildings suppresses ICE’s traditional channel for interior arrests, producing statistically meaningful reductions in arrests stemming from local custody [1].
3. ICE adapts: public-facing arrests and at-large operations obscure the full effect
The statistical impact of non-cooperation is constrained by ICE’s ability to shift tactics: as jail access narrows, the agency has increased public-facing arrests at courthouses, workplaces, check-ins and in neighborhoods—trends visible in multiple datasets showing tripling of raw arrests in some regions even as per-capita rates remain low [3] [4]. Reporting and DHS statements emphasize that a large share of recent arrests involve people with criminal histories, a claim DHS uses to justify aggressive interior enforcement; analysts counter that ICE’s pivot to at-large tactics and increased use of alternatives to detention and new detention beds complicates direct comparisons [6] [9].
4. Detention totals reflect both local cooperation and federal resource expansion
Detention levels are a product of arrest pipelines plus federal capacity: ICE’s expansion of beds, contracts and new facilities has driven detention population growth irrespective of some local non-cooperation, with advocacy groups documenting a sharp rise in detained people—reports show detention counts jumping markedly in 2025 and a large increase in people without criminal records held on any given day [10] [11]. TRAC and ICE administrative counts confirm substantial daily populations and that many detained persons were arrested by ICE itself rather than directly transferred from local jails, underscoring that state non-cooperation reduces but does not eliminate detention inflows [7] [5].
5. What the numbers cannot fully settle and where research should go next
Available datasets—ICE’s public stats, FOIA-derived Deportation Data Project tables and independent analyses—allow robust correlations between cooperation levels and lower jail-origin ICE arrests, but they cannot fully isolate causal effects from confounders like enforcement priorities, geographic migration patterns, or tactical adaptation without longitudinal, matched-county studies; existing reporting documents trends and mechanisms but concedes limits on attributing all detention changes to state policy alone [4] [12]. Alternative viewpoints from DHS and pro-enforcement sources argue that sanctuary policies harbor dangerous individuals and that ICE’s shifted tactics prove robust enforcement capacity, a perspective that should be tested against microdata linking local policy changes to downstream arrest and detention outcomes [6].