How do state sanctuary policies statistically affect ICE interior arrest rates?
Executive summary
Sanctuary policies are statistically associated with fewer deportations and lower ICE arrest rates in some jurisdictions—especially arrests originating in local jails—because those policies limit local cooperation with ICE detainer requests and notifications [1] [2] [3]. At the same time, federal capabilities, changing enforcement priorities, and alternate arrest tactics mean sanctuary laws do not make jurisdictions immune from ICE interior arrests, and national arrest totals can rise even as sanctuary jurisdictions see relatively fewer jail-originating handoffs [4] [5] [6].
1. How researchers measure the effect: jails, detainers and “origin of arrest”
Empirical studies and policy explainers typically isolate the impact of sanctuary policies by measuring arrests and deportations that originate in local jails—because detainer requests and release notifications are the primary tools ICE uses to transfer custody from local to federal authorities—so jurisdictions that refuse to honor detainers tend to produce fewer ICE arrests from those jails [1] [2]. The Migration Policy Institute notes that only a subset of ICE removals come from the interior versus the border, with ICE responsible for an average of roughly 43,000 removals annually of noncitizens arrested in the U.S. during 2020–24, underscoring why local-jail cooperation materially shapes interior arrest flows [2].
2. What the peer‑reviewed evidence shows: reduced deportations, no spike in violent crime
A widely cited PNAS study concluded that sanctuary policies reduced deportations without increasing crime, and found no evidence that local sanctuary policies prevented deportations of people with violent convictions—meaning policies reduced removals overall while not measurably changing rates of violent-crime deportations in the studied period [1]. The American Immigration Council summarizes similar findings and broader literature indicating that sanctuary policies “do not threaten public safety” and are correlated in some analyses with neutral or even lower crime indicators [7].
3. Where sanctuary policies blunt ICE power—and where they don’t
Local and state restrictions on honoring ICE detainers and on sharing release times make it harder and costlier for ICE to execute many interior arrests tied to local bookings; organizations tracking state-level enforcement note that a large share of ICE interior arrests historically originate from local custody, so reducing jail cooperation can substantially lower those transfers [3] [6]. However, reporting from Stateline and national outlets documents that ICE can and does conduct arrests outside jails—community arrests, workplace operations and targeted federal-led raids—so sanctuary laws constrain a significant channel of interior arrests but do not eliminate federal operations conducted independently [4] [5].
4. The role of enforcement priorities, resources and legal tools
Federal agency posture and resources shape outcomes: ICE’s Enforcement and Removal Operations describes its broad statutory authority to make interior arrests and to prioritize those it deems threats to public safety—authority that is independent of local policy choices—so when DHS shifts to more aggressive national tactics or increases funding for interior operations, sanctuary policies face limits in insulating communities from higher overall arrest counts [8] [9]. Recent reporting and analyses also show that expanded detention capacity and mission changes can increase arrests of people without criminal records, diluting the protective effect sanctuary policies have on reducing certain categories of deportations [10] [5].
5. State examples and statistical nuance
Case studies illustrate variance: Northern California, credited by researchers and local analysts with maintaining one of the nation’s lowest ICE arrest rates, is attributed in part to California’s sanctuary law and complementary local practices—evidence that strong state-level limits on cooperation can produce measurable reductions in ICE activity regionally [11]. Conversely, high-profile sanctuary cities have still experienced ICE operations and community arrests, reinforcing that sanctuary policy effects are conditional on enforcement tactics, judicial rulings, and whether ICE pivots to non-jail arrest strategies [4] [12].
Conclusion: a conditional, measurable effect
The best synthesis of available reporting and scholarship is clear: sanctuary policies statistically reduce ICE interior arrests and deportations that rely on local-jail cooperation and detainer mechanisms, and they do so without evidence of increasing violent crime [1] [7] [2]; however, they are not a shield against all federal arrests because federal resources, alternative arrest strategies, and agency priorities can offset some of that protective effect at the national level [8] [5] [4]. Where data are incomplete—especially rapid changes in enforcement tactics and post‑2024 arrest patterns—more granular, longitudinal state-level arrest data are needed to quantify how much sanctuary policies blunt overall ICE arrest growth versus simply shifting the locus and method of federal enforcement [6] [3].