Faculty of law blogs / UNIVERSITY OF OXFORD

Sanctuary Policies, Immigration, and Public Safety



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5 Minutes

Post by Daniel E. Martínez, Associate Professor, School of Sociology, University of Arizona and Ricardo D. Martínez-Schuldt, Assistant Professor, Department of Sociology, University of Notre Dame


US immigration law falls under the purview of the federal government. Nevertheless, a series of policy changes in the 1990s led to the devolution of immigration enforcement from the federal level to the local level. Consequently, local officials in certain jurisdiction are increasingly involved in policing immigration. Some state, county, and municipal officials have responded by enacting policies that limit cooperation between local authorities and the federal government in the enforcement of immigration law. Though varying in form and function, these initiatives are often described colloquially as sanctuary policies and the areas that implement them are frequently referred to as immigrant sanctuary states, counties, or cities.

Though immigrant sanctuaries have existed in the United States since the 1980s, nationwide attention to these policies increased after a deportable Mexican national was involved in a high-profile act of violence in a California sanctuary city in July 2015. The incident initiated a renewed policy debate over the relationship between sanctuary cities and public safety, in particular. One of Donald Trump’s first executive orders as president, just days after he took office, threatened to withhold federal funding from sanctuary jurisdictions because such policies have “caused immeasurable harm to the American people and to the very fabric of [the] Republic.” In addition, the Trump administration challenged a 2017 bill in California that limits the exchange of information between state law enforcement officials and federal authorities in matters of immigration enforcement. Recently, the US Supreme Court refused to hear an appeal after lower courts ruled against the Trump administration’s challenge.

Opponents of sanctuary policies—including the Trump administration—have argued that the policies threaten communities by attracting criminals or by shielding deportable noncitizen offenders from deportation. Critics of sanctuary policies routinely draw on narratives vilifying immigrants, especially unauthorized Mexicans, as criminals to support their assertion. Proponents have countered that sanctuary policies improve public safety by removing the fear of deportation thereby (1) fostering positive community-police relations, (2) encouraging immigrants to cooperate with law enforcement investigations, and (3) increasing immigrants’ willingness to report crime victimization to authorities (Lyons, Velez, and Santoro 2013).

Despite the pervasive tropes about immigrant criminality as well as the heighted attention on a possible sanctuary-crime link among policymakers, few empirical studies have examined the relationship between sanctuary policies and public safety. We aimed to expand upon the existing body of research by addressing two interrelated research questions: (1) how, if at all, is the adoption of a city-level sanctuary ordinance associated with changes in city-level incidents of homicide and robbery? (2) What, if any, is the relationship between unauthorized Mexican immigrant concentration and violent crime in US cities?

Sanctuary Policies, Undocumented Mexican Immigration, and Violent Crime

We addressed these questions by examining trends in the number of homicides and robberies before and after the adoption of sanctuary ordinances across 107 cities the United States between 1990 and 2010. We reported our empirical findings in a 2019 article published in Justice Quarterly, and shared our study at the third installment of the “Congressional ‘Ask a Criminologist’ Series” in Washington, DC the summer of the same year.

Overall, we found no direct relationship between sanctuary policies and homicide. Similarly, we found no evidence that the concentration of unauthorized Mexican immigrants was associated with either measure of violent crime. However, we found that the cities experienced a decline in robberies after they adopted sanctuary policies.

We uncovered more complex relationships between sanctuary policies, immigration, and violent crime. We found that increases in the foreign-born population and increases in the unauthorized Mexican immigrant population were each associated with a reduction in homicide, but only in sanctuary cities. Moreover, an increase in the percentage of the foreign-born population was associated with a reduction in robberies, but again, only in immigrant sanctuaries.

Our findings are consistent with those from the few existing empirical studies that have examined the “sanctuary-crime” link. No prior study has found support for a positive association between sanctuary policies and crime. The consensus in the literature, based on empirical data, is that the adoption of sanctuary policies does not lead to higher rates or incidents of crime. Using distinct data sources and different analytic techniques, research has found either no relationship or a negative relationship between the implementation of sanctuary ordinances and crime (for instance, see Lyons et al. (2013), Wong (2017), Gonzalez, Collingwood, and El-Khatib (2017), and Kubrin and Bartos (2020)).

Motivation for Additional Analyses

Given the findings presented in our Justice Quarterly article, we wanted to explore the possible mechanisms by which sanctuary policies might increase public safety. As proponents claim, sanctuary policies may increase public safety by encouraging members of immigrant communities to report crime victimization to law enforcement. Nevertheless, researchers had not examined whether the implementation of a sanctuary policy affects individual-level behavior, such as notifying law enforcement if one was the victim of a crime.

Research Questions and Methodology of Forthcoming Article

Given the conjecture in the literature regarding the mechanism through which sanctuary policies might promote public safety, we posed the following research questions: (1) what, if any, is the relationship between sanctuary policies and crime victims’ likelihood of reporting their victimization to law enforcement? And (2) is there any evidence of moderation, such that the adoption of sanctuary ordinances increases the odds that members of certain ethno-racial groups (i.e., Latinos) report their victimization compared to members of other groups.

We addressed these questions in a forthcoming American Sociological Review article by drawing on and merging a variety of publicly-available data sources, including the National Crime Victimization Survey (NCVS): MSA Data, the National Immigration Law Center’s list of sanctuaries, the US Decennial Census (1980, 1990, and 2000), and pooled data from the American Community Survey (ACS, 2005-2009).

Our analyses focused on the relationship between the passage of sanctuary ordinances and crime victimization reporting between 1980 and 2004. After combining data from our sources, we had complete information on more than 35,000 incidents of violent crime victimization, with these incidents having occurred across 25 years in 40 different metropolitan statistical areas (MSA) in the United States.

We expected that members of immigrant communities would be the most responsive to the passage of sanctuary policies. Because the NCVS does not inquire about respondents’ immigration status, we focused on examining the effects of sanctuary policy adoption on Latino crime victims’ reporting behavior because Latinos were more likely to be foreign-born, unauthorized immigrants, or members of mixed-status families during our study period. 

Findings from forthcoming American Sociological Review Article

We found that Latino victims were more likely to report violent crime victimization after sanctuary policies were adopted within their MSAs of residence. The probability that Latinos, on average, reported violent crime victimization to law enforcement increased by 11.6 percentage points (from 49.8% to 61.4%) after sanctuary policies were passed. We did not find any evidence that reporting behavior systematically differed for other ethno-racial groups. Our main finding, which demonstrates an increase in the probability that Latinos report violent crime victimization post-sanctuary policy adoption, supported our hypothesis and is consistent with the expectations of sanctuary policy proponents.


Overall, the findings from our two studies strongly suggest, first, that the implementation of sanctuary policies does not lead to higher rates of violent crime. In fact, we find that such ordinances are associated with a decrease in robbery incidents at the city-level. Second, the passage of sanctuary policies may actually promote public safety by encouraging Latino crime victims (or crime victims most socially-connected to immigrant communities) to report violent victimization to law enforcement.

Though additional research should attempt to replicate these results, our empirical findings make a strong case for the expansion of policies limiting cooperation between local law enforcement agencies and federal officials in the enforcement of immigration law in the United States. Due to fears of possible deportation, cooperation between local authorities and federal officials in matters of immigration enforcement may actually undermine public safety by keeping people from coming forward when they have been the victims of violent crime.

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How to cite this blog post (Harvard style) 

Martínez, D. E. and Martínez-Schuldt, R. D. (2021). Sanctuary Policies, Immigration, and Public Safety. Available at: https://www.law.ox.ac.uk/research-subject-groups/centre-criminology/centreborder-criminologies/blog/2021/01/sanctuary [date]

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