What do peer‑reviewed studies say about comparative homicide and incarceration rates for undocumented immigrants?
Executive summary
Peer‑reviewed empirical studies and government‑funded analyses consistently find that undocumented immigrants have lower measured homicide arrest rates and lower incarceration rates than U.S.‑born residents, and that increases in immigrant populations are not linked to rises in violent crime; these conclusions are reported across multiple academic articles and NIJ‑funded research [1] [2] [3] [4]. However, the literature also warns of measurement challenges—especially estimating undocumented populations and separating arrests from actual offending—which limit how precisely those gaps can be quantified [1] [2] [5].
1. Homicide and violent‑crime findings: arrests and trends
Multiple peer‑reviewed studies and large empirical analyses report that undocumented immigrants exhibit lower homicide arrest rates than native‑born Americans, and that jurisdictions with rising undocumented populations do not show corresponding increases in homicide or violent crime; for example, an NIJ‑funded Texas study found undocumented people had the lowest homicide arrest rates across the study period, averaging less than half the arrest rate of U.S.‑born citizens [1] [6], while a longitudinal analysis using state fixed‑effects found no evidence that increases in undocumented immigration raise state homicide, robbery, assault, or rape rates after accounting for lawful immigration and other controls [2]. Advocacy and research organizations likewise document city‑ and state‑level patterns in which immigrant concentration correlates with stable or declining violent crime, though they frame it as association rather than strict causation [7] [8].
2. Incarceration rates: long‑run and cross‑sectional evidence
Longitudinal and historical work shows immigrants—broadly defined—are incarcerated at rates equal to or lower than U.S.‑born people, and recent multi‑decade studies extend that gap to modern periods: a 150‑year analysis found immigrants have never been incarcerated at higher rates than the U.S.‑born and that the gap has widened recently, with immigrants substantially less likely to be incarcerated [3] [4], while other researchers using Texas and national data report undocumented immigrants are significantly less likely to be arrested or convicted for violent, drug, and property crimes than native‑born residents [1] [5]. Major syntheses and policy briefs from academic and nonprofit centers reiterate that incarceration rates among immigrant men, including likely undocumented groups, tend to be below national norms [9] [8].
3. Methodological caveats and data limitations
Researchers consistently flag methodological constraints: crime incident data rarely record immigration status, so studies depend on arrest records, correctional censuses, and population estimates for undocumented residents (often from the Center for Migration Studies), and results are sensitive to those denominators and to whether analyses measure arrests, convictions, or incarcerations [1] [2] [5]. Studies note large shares of homicides go unsolved—complicating homicide‑rate comparisons—and some population estimation methods produce divergent counts of the undocumented population, which can shrink or enlarge calculated offense rates [6] [5]. Analysts also emphasize that correlation at city or state levels does not prove causal mechanisms; social integration, selection effects of who migrates, and local policing practices are plausible mediators that studies attempt to control for but cannot eliminate entirely [2] [7].
4. Where the consensus lies — and where debate remains
The peer‑reviewed and government‑funded evidence converges: undocumented immigrants are not driving homicide or incarceration increases and, by multiple metrics, have lower arrest and incarceration rates than U.S.‑born people [1] [4] [3]. Remaining debates center on magnitude and mechanisms—how much of the gap reflects self‑selection, enforcement differences, or measurement error—and on translating these findings into policy amid political narratives that portray migrant crime waves; scholars and policy groups caution against overgeneralizing from individual high‑profile crimes and urge careful use of data in policymaking [8] [7] [10].
5. Bottom line for interpretation and policy discourse
Peer‑reviewed studies and government analyses uniformly undermine the claim that undocumented immigration increases homicide or incarceration rates and instead show lower measured offending and incarceration for undocumented populations, but responsible interpretation requires attention to data limitations and the difference between arrests and actual offending; researchers recommend continued investment in better population estimates and transparent reporting rather than relying on isolated incidents or politicized anecdotes [1] [2] [5].