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Illegal Immigrants and Crime

One of the problems in doing research on crime is that most research is constrained to the variables that our national crime statisticians have chosen to collect.  Often the variables of interest to a researcher are not collected, and those that are collected are a poor proxy.

On the question of immigration and crime, we often hear the statistic that the crime rate among immigrants is lower than the rate among native-born Americans.  That statistic is virtually irrelevant for those whose primary interest is illegal immigration.  Can we simply assume that legal and illegal immigrants are the same in this regard?  That would be a huge and dubious assumption, yet it is implicit in arguments we hear all the time.

John Lott has this study at SSRN using data from Arizona, which does track the immigration status, including legality, of its prisoners.  Here is the abstract:
Using newly released detailed data on all prisoners who entered the Arizona state prison from January 1985 through June 2017, we are able to separate non-U.S. citizens by whether they are illegal or legal residents. Unlike other studies, these data do not rely on self-reporting of criminal backgrounds. Undocumented immigrants are at least 142% more likely to be convicted of a crime than other Arizonans. They also tend to commit more serious crimes and serve 10.5% longer sentences, more likely to be classified as dangerous, and 45% more likely to be gang members than U.S. citizens. Yet, there are several reasons that these numbers are likely to underestimate the share of crime committed by undocumented immigrants. There are dramatic differences between in the criminal histories of convicts who are U.S. citizens and undocumented immigrants.

Young convicts are especially likely to be undocumented immigrants. While undocumented immigrants from 15 to 35 years of age make up slightly over two percent of the Arizona population, they make up about eight percent of the prison population. Even after adjusting for the fact that young people commit crime at higher rates, young undocumented immigrants commit crime at twice the rate of young U.S. citizens. These undocumented immigrants also tend to commit more serious crimes.

If undocumented immigrants committed crime nationally as they do in Arizona, in 2016 they would have been responsible for over 1,000 more murders, 5,200 rapes, 8,900 robberies, 25,300 aggravated assaults, and 26,900 burglaries.

Attorney General Sessions noted this research in his speech in Norfolk, Virginia last Friday.

Lott is, of course, controversial, and his work has been criticized.  But anyone whose work comes up with Politically Incorrect results will be savaged by today's politically corrupted academia, so such criticism must be taken with a grain of salt.


I hope you will post an update now that it turns out Lott was wrong. Of course he is as politically as corrupted as anyone could be, so no surprise. https://www.cato.org/blog/fatal-flaw-john-r-lott-jrs-study-illegal-immigrant-crime-arizona

Nowrasteh's criticism was only published today, so Lott hasn't had a chance to respond yet. I am not about to assume that a critic is necessarily right and the original study is necessarily wrong.

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