The idea undocumented immigrants bring an influx of crime is a claim repeated so often it's widely assumed to be true. Instead, the reverse is the case, at least in Texas, according to the first study to test it directly. Facts are often powerless to change a popular narrative on such an emotive issue, but it’s scientists' duty to find them anyway.
The belief undocumented immigrants (often referred to as illegal immigrants) are drivers of crime is so pervasive it was the cornerstone of a submission to the US Supreme Court this year, but there was almost no evidence to support it.
Dr Michael Light of the University of Wisconsin-Madison obtained access to the data on 1.8 million arrests in Texas between 2012 and 2018. Light and colleagues compared the proportion of crime committed by immigrants with their share of the Texas population, and then further broke this down between those with legal permission for entry and those without.
In Proceedings of the National Academy of Sciences, Light and co-authors report results that are very clear: Undocumented immigrants are drastically less likely to be arrested for a wide range of crimes than either US citizens or those with permits. Their arrest rate is half that of US-born citizens for violent crimes, and even lower for homicide. They are only 40 percent as likely to be arrested for drug crimes, which drops to a quarter for property crimes. Legal immigrants fall around halfway between the two groups on every measure other than for traffic violations, where they outnumber either group.
Calculations like this rely on estimates of the number of people living in the state without formal recognition, which are naturally somewhat imprecise. Yet the paper notes the differences are so stark even a substantial downward revision of immigrant numbers would barely change the conclusion.
Studies worldwide have long shown that legally approved immigrants are less likely to commit crimes than native-born citizens. However, a lack of data has prevented the question from being properly tested for those without papers. Previous studies have either relied on unreliable proxy measures or have not been peer-reviewed. Their results conflicted with each other. Unlike other states (and many countries), Texas reliably records the immigration status of arrestees, giving Light the means to properly investigate the issue for the first time.
The paper notes that “the federal government now spends more on immigration enforcement than all other principle criminal law enforcement agencies combined.” As Light pointed out in a statement: "If the plan was to make communities safer… through deportation, it did not deliver on that promise."
Arrests and crime rates are not identical of course. Theoretically undocumented immigrants might be committing as many crimes as their counterparts but seldom being arrested. However, it strains credibility to believe police forces are going easy on undocumented immigrants.
The results are similar if convictions replace arrests as the metric used.