What evidence links sanctuary policies to changes in crime rates or public‑health outcomes?
Executive summary
A growing body of peer-reviewed research finds no evidence that sanctuary policies increase crime, and several studies link such policies to reductions in certain property crimes and improved crime‑reporting by immigrant victims, while public‑health research documents harms from aggressive immigration enforcement that sanctuary practices can mitigate [1] [2] [3] [4]. However, the literature is limited, heterogeneous in definitions and methods, and produces mixed localized effects—meaning strong national claims on either side overreach the evidence [5] [6].
1. What the crime data show: null or modestly beneficial effects
Multiple rigorous, longitudinal analyses conclude that sanctuary or limited‑cooperation policies do not increase crime and, in several cases, are associated with declines in property crime or robberies; for example, a PNAS analysis saw about a 7% drop in property crime and no change in violent crime following sanctuary policy adoption in dozens of cities [1], and other county‑level work reports within‑county decreases in violent and property crime after sanctuary practices were adopted [7] [8]. Complementary city‑level and matching studies generally find no discernible difference in violent, rape, or property crime rates after sanctuary ordinances, and some studies report lower robbery rates in areas with higher immigrant concentrations [2] [9] [10].
2. Reporting behavior and the “trust spiral” explanation
Researchers offer a mechanism: sanctuary policies increase institutional trust among immigrants, which raises reporting of victimization and engagement with formal labor and housing markets, producing social integration that can reduce reliance on illegitimate markets and lower crime—evidence shows Latinos become more likely to report violent victimization after sanctuary policies are adopted [3] [11]. Some increases in reported sexual‑assault cases in granular precinct analyses appear driven by improved reporting rather than higher incidence, consistent with the theory that sanctuary measures change behavior toward police [9].
3. Public‑health outcomes: enforcement harms and sanctuary as mitigation
Public‑health and social‑science observers characterize immigration enforcement as a social determinant of health that reduces access to care and raises stress and marginalization; organizations and reviews link aggressive enforcement to worse mental and physical health and lowered use of public benefits among Latino communities, effects sanctuary practices aim to blunt [4] [7]. Advocates such as NILC synthesize studies showing sanctuary jurisdictions report higher median household income, less poverty and stronger labor metrics—indirect markers of population health and prosperity—though these are associations that require careful causal interpretation [12].
4. Methodological limits and why results are mixed
The scholarship is limited in number, varies widely in how “sanctuary” is defined (city ordinance, refusal to honor ICE detainers, or broader immigrant‑friendly policies), and faces selection and omitted‑variable challenges because jurisdictions that adopt these policies differ politically and demographically from those that do not [5] [13]. Cross‑sectional comparisons risk reverse causality, and some papers note uneven effects by urban density, immigrant concentration, and timing of federal programs like Secure Communities, so local studies can show heterogenous outcomes even if broad trends point to null or beneficial effects [13] [4].
5. Political narratives, hidden agendas, and costs
Federal rhetoric framing sanctuary jurisdictions as public‑safety hazards has been used to justify enforcement interventions and to shift political pressure onto local officials, but several studies and nonprofit analyses argue that cooperation with ICE imposes fiscal and community costs while yielding little public‑safety benefit—estimates cited include billions in coordination costs for jurisdictions and documented savings tied to sanctuary approaches, though such figures derive from advocacy and academic estimates that reflect different methods and priorities [12] [4] [13]. Opponents point to anecdotal violent‑crime cases as proof of danger, but the peer‑reviewed record does not support a robust causal link between sanctuary policies and rising crime [5] [1].
6. Bottom line: evidence supports safety or neutrality, not harm
The best available empirical evidence indicates that sanctuary policies do not raise crime and in numerous analyses are associated with reduced property crimes, improved reporting by immigrant victims, and social‑health benefits tied to greater access to services, while methodological caveats—variable definitions, selection bias, and local heterogeneity—mean conclusions should be cautious and context‑specific rather than absolutist [1] [3] [5] [9]. Where questions remain, they are about mechanisms and local implementation, not a clear, generalizable harm from sanctuary policies.