How illegal immigrants affect crime is one of the most contentious subareas of debate in the entire immigration issue. Cato scholars have produced much original research on this topic, finding that illegal and legal immigrants both have lower incarceration rates than native-born Americans and lower criminal conviction rates in the state of Texas, the only state where data are available. We’ve also found that local government participation in immigration enforcement programs doesn’t affect crime rates.

Academic researchers have also stepped into the fray. Sociologists Michael Light and Ty Miller found that a higher illegal immigrant population does not increase violent crime rates. Those two researchers then teamed up with Purdue sociologist Bryan C. Kelly to look at how higher illegal immigrant populations affected drug arrests, drug overdose deaths, and DUI arrests. They found large and significantly associated reductions in drug arrests, drug overdose deaths, and DUI arrests with no significant relationship between increased illegal immigration and DUI deaths. Further research by other criminologists also found that illegal immigrants report engaging in less crime prior to and following their first arrest than legal immigrants and native-born Americans.

A recent paper by Christian Gunadi, an economist at the University of California Riverside, also found that illegal immigrants are 33 less likely to be institutionalized than native-born Americans despite possessing characteristics usually associated with higher crime rates. Gunadi’s study is especially heartening to read as he started with methods adapted by Michelangelo Landgrave and myself, improved upon them, and came to a result that is similar to ours. Gunadi found a smaller difference between native-born and illegal immigrant incarceration rates, that they are one-third below natives rather than 50 percent below, but there’s no arguing with his better methods. It’s especially gratifying to see the academy take notice of our empirical methods developed in policy briefs and improve upon them for peer-reviewed journals.

Another recent working paper by Annie Laurie Hines and Giovanni Peri used fluctuations in immigration enforcement policy and its effect on deportations to see how local crimes rates were affected. If illegal immigrants were more crime-prone than other groups, then the reduction of deportations and immigration enforcement should have resulted in relative increases in crime rates or a slower rate of decline. Nothing of the sort occurred. Similar to other research on how Secure Communities affected crime, the pace of deportations did not affect the crime rate.

The impact of immigration on crime is an important topic for further research. It’s wonderful to see serious academics like those above dive into investigating how illegal immigrants affect crime. I’ll be keeping a close eye on these research developments as they occur.