Findings in a March 2017 study by the libertarian Cato Institute also support Villaraigosa's statement:

"Illegal immigrants are 44 percent less likely to be incarcerated than natives. Legal immigrants are 69 percent less likely to be incarcerated than natives. Legal and illegal immigrants are underrepresented in the incarcerated population while natives are overrepresented."

The Cato study used information from the U.S. Census Bureau's American Community Survey for immigrants aged 18 to 54 who are incarcerated in the United States. 

To examine Villaraigosa's claim, we also relied on research into similar claims by our partner national PolitiFact. In July 2016, it rated Mostly True a statement by Libertarian candidate for president Gary Johnson that Mexican immigrants "are more law-abiding than U.S. citizens and that is a statistic."

PolitiFact found several studies that back up this claim by citing incarceration rates. It also found groups that challenged those studies or said more research is needed.

PolitiFact’s findings

PolitiFact pointed to a July 2015 report by the American Immigration Council, a pro-immigrant nonprofit in Washington. The council analyzed data from the Census’ 2010 American Community Survey and found that about 1.6 percent of all immigrant males (Census does not specify legal status) between 18 and 39 years old were incarcerated, compared to 3.3 percent of the native-born population.

Looking at California prisons, immigrants are also underrepresented. U.S.-born men are incarcerated in the state at a rate of more than two-and-a-half times greater than that of foreign-born men, according to a study by the Public Policy Institute of California.

The American Immigration Council also reported that 2010 Census data shows incarceration rates of young, less educated Mexican, Salvadoran and Guatemalan men — which comprise the bulk of the unauthorized population — are "significantly lower" than incarceration rates of native-born young men without a high-school diploma.

Specifically for Mexican men ages 18 to 39, the incarceration rate in 2010 was 2.8 percent, compared to 10.7 percent for native-born men in the same age group, the council’s report said.

Immigrants come to the United States to build better lives for themselves and their children, said Walter A. Ewing, a senior researcher at the American Immigration Council and one of the report’s authors.

"They are very motivated to not blow that opportunity by getting in trouble with the police," he told PolitiFact. "This is especially so for unauthorized immigrants, who can be deported at any time for unlawful presence."

Crime trends

PolitiFact also noted that as the immigrant population has increased, crime has gone down, citing Ewing’s report.

Between 1990 and 2013, the foreign-born share of the U.S. population increased from 7.9 percent to 13.1 percent, and the number of unauthorized immigrants went up from 3.5 million to 11.2 million. At the same time, the violent crime rate (murder, rape and aggravated assault) decreased 48 percent and property crime rate fell 41 percent, the report said, citing FBI data.

Bianca E. Bersani, an assistant professor and director of the Criminology and Criminal Justice Program at the University of Massachusetts in Boston, says her research also shows that crime involvement among foreign-born residents is lower than that of U.S.-born citizens.

"The rhetoric of the ‘criminal immigrant’ does not align with the bulk of empirical research," Bersani said.

According to Bersani’s research, while first-generation immigrants are less likely to commit crimes than the native-born population, the second generation (individuals born in the United States to at least one foreign-born parent) more closely resemble patterns of their native-born peers (three or more U.S.-born generations).

"This does not suggest that the second generation is uniquely crime prone, but instead that they are acting in ways that are no different from the rest of the U.S.-born population," Bersani said.

Datasets with information on both crime and immigrant status are rare, Bersani said, though more research and data are becoming available.

More research needed?

The Center for Immigration Studies, which supports stricter immigration policies, in a 2009 study said that overall understanding of immigrants and crime "remains confused" due to lack of data and contrary information.

Unless inmates are identified as immigrant or native-born, incarceration rates are a poor way to measure links between immigrants and crime, the study said.

As PolitiFact reported in 2015, there isn’t exact data on how many undocumented immigrants are currently incarcerated.

PolitiFact California spoke about this critique with Ewing of the American Immigration Council, whose research supports Villaraigosa’s claim. He said he’s confident in the work that’s been done and said critics have used anecdotes, rather than full-blown research, to try to make their points.

Ewing added that the studies backing up Villaraigosa’s statement are "from such a wide range of researchers using so many different methodologies and sources of data -- not everyone can be wrong."

Our ruling

Villaraigosa said "undocumented immigrants commit less crimes than the native born."

He cited a 2015 study by the National Academy of Sciences that backs up this claim.

In a fact check last year, PolitiFact rated a similar claim Mostly True. It cited additional studies by scholars and partisan groups that show that the foreign-born population is less likely to commit crimes than the native-born.

It also found that researchers agree more data is needed to get a better understanding of immigration and crime. It said this was a needed clarification.

PolitiFact California agrees with these findings.

We rated Villaraigosa’s claim Mostly True.

https://www.politifact.com/california/statements/2017/aug/03/antonio-villaraigosa/mostly-true-undocumented-immigrants-less-likely-co/