Does Undocumented Immigration Increase Violent Crime?

“At a minimum, the results of our study call into question claims that undocumented immigration increases violent crime. If anything, the data suggest the opposite.”

Michael T. Light and Ty Miller

“Our findings suggest that undocumented immigration over this period is generally associated with decreasing violent crime. The negative association between unauthorized immigration and violence is evident in both police reports and victimization data; simple procedures such as bivariate associations; more stringent multivariate tests in which numerous theoretically relevant measured and unmeasured confounding variables are accounted for; instrumental variable analyses that model the selective migration patterns of undocumented immigrants; and a variety of supplemental models and sensitivity analyses. Indeed, of the 57 point estimates reported throughout our analysis (including in the online supporting information), not one shows a positive association between undocumented immigration and violent crime.”

“In reference to public policy, at the most basic level, our study calls into question one of the primary justifications for the immigration enforcement build-up. Debates about the proper role of undocumented immigrants in U.S. society will no doubt continue, but they should do so in light of the available evidence. For this reason, any set of immigration policies moving forward should be crafted with the empirical understanding that undocumented immigration does not seem to have increased violent crime. This analysis also speaks to the unintended consequences of border enforcement. Although immigration enforcement may have “backfired” by increasing the population of undocumented immigrants (Massey, Pren, and Durand, 2016), this policy blunder has not come at the expense of public safety. This finding provides clarifying context for why the most ambitious policies aimed at removing “criminal aliens” have not yielded sizeable reductions in crime. For example, the Immigration and Customs Enforcement’s Secure Communities (S-Comm) Program was designed specifically as a crime-fighting initiative to identify and deport criminal aliens through state and local collaboration with federal immigration authorities. Despite the fact that by 2013 S-Comm was active in nearly every county and the deportation of aliens with criminal records increased substantially under the program, the results of comprehensive analyses revealed no impact of S-Comm on violent crime (Miles and Cox, 2014; Treyger, Chalfin, and Loeffler, 2014). Our results help explain why; undocumented immigrants do not increase violence.”

“Although ardent skeptics may remain unconvinced, the weight of the evidence presented here and in supporting work challenges claims that unauthorized immigration endangers the public. At a minimum, the results of our study call into question claims that undocumented immigration increases violent crime. If anything, the data suggest the opposite.”

[Excerpts from Light, Michael T. and Ty Miller. 2018. “Does Undocumented Immigration Increase Violent Crime? ” Criminology 56(2): 370–401. doi: 10.1111/1745-9125.12175. Full .pdf of Light and Miller’s (2018) article here. Emphasis and hyperlinks not in original. References from Light and Miller (2018) reproduced below.]

• Massey, Douglas S., Karen A. Pren, and Jorge Durand. 2016. Why border enforcement backfired. American Journal of Sociology 121:1557–600.
• Miles, Thomas J., and Adam B. Cox. 2014. Does immigration enforcement reduce crime: Evidence from secure communities. Journal of Law and Economic 57:937–73.
• Treyger, Elina, Aaron Chalfin, and Charles Loeffler. 2014. Immigration enforcement, policing, and crime. Criminology & Public Policy 13:285–322. [Earlier draft available here.]