Violent criminals among illegal aliens
Executive summary
A substantial and growing body of empirical research finds that undocumented immigrants are not a disproportionate source of violent crime and in many studies have lower violent-offending and arrest rates than U.S.-born residents [1][2][3]; nevertheless, isolated high-profile violent incidents and government counts of “criminal aliens” are used politically to paint a different picture [4][5].
1. What the best empirical studies say about violent offending
Large, peer‑reviewed analyses using administrative arrest and incarceration records repeatedly show undocumented immigrants have lower rates of violent crime than native‑born Americans: a Texas study using comprehensive arrest records found undocumented immigrants were arrested at less than half the rate of U.S.‑born citizens for violent crimes [1][2], and National Institute of Justice summaries report similar patterns [2]; meta‑reviews and academic syntheses likewise conclude that undocumented immigration generally does not increase violent crime and can be associated with stable or falling violent‑crime trends [6][5].
2. Why Texas data matter — and what they show
Texas is often cited because it uniquely records arrestee immigration status and thus enables direct comparisons; that PNAS/NIJ analysis of Texas Department of Public Safety records from 2012–2018 found consistently lower felony and violent‑felony arrest rates among undocumented immigrants than among U.S.‑born residents, a finding robust across offense types and alternative measurement approaches [1][3][2].
3. National patterns and long‑run trends
At the national and city levels, multiple researchers and policy centers document that rising immigrant shares have coincided with large declines in violent and property crime over recent decades — for example, aggregate violent crime fell substantially even as the immigrant fraction of the population increased — and state‑level analyses find no systematic positive correlation between immigrant concentration and total crime [7][8][9][10].
4. The counterarguments, data that can be cited differently, and political uses
Federal enforcement data and border‑agency tallies list individuals classified as “criminal aliens” after records checks, and those counts are highlighted by policymakers to argue immigrant criminality is a crisis [4]; researchers caution that such administrative tallies can reflect varied definitions (prior convictions, foreign convictions, or immigration‑related offenses) and do not equate to a population‑level crime rate without an appropriate denominator and context [4]. Additionally, some scholarship notes heterogeneity by origin or locale — a minority of studies find localized associations under specific conditions, and one earlier analysis raised the possibility of different patterns for certain origin groups [6]. Political actors, as the Brennan Center and other analysts note, often amplify individual high‑profile crimes to create a perception of a “migrant crime wave” that empirical analysis does not substantiate [5].
5. Limitations, measurement problems, and where uncertainty remains
Comparing crime across immigration status faces consistent challenges: undocumented populations are hard to enumerate precisely (affecting rate calculations), reporting biases and differential policing can skew arrest data, and many analyses rely on arrests or incarcerations as proxies for offending rather than convictions or victimization surveys — caveats that scholars explicitly acknowledge even when findings point to lower rates among undocumented immigrants [6][3]. Where local data are incomplete or where studies lack immigration‑status identifiers, researchers urge caution about generalizing from arrest counts alone [6][4].
6. Bottom line
A preponderance of high‑quality evidence in academic and government‑funded research finds undocumented immigrants are not responsible for higher violent‑crime rates and are often less likely to be arrested for violent offenses than native‑born residents [1][2][3]; nonetheless, administrative “criminal alien” tallies and selective media coverage fuel public and political perceptions to the contrary, and measurement limitations mean vigilance is required when translating arrest counts into broad claims about population criminality [4][5][6].