A crime researcher and the open-borders Cato Institute are dueling over criminal illegal aliens in Arizona. Either way, the numbers look bad for public safety.

John Lott, who heads the Crime Prevention Research Center in Arlington, Va., says illegal immigrants are “at least 142 percent more likely to be convicted of a crime than other Arizonans.”

In the first in-depth analysis of criminal convictions distinguishing between legal and illegal immigrants, Lott found that illegal aliens in the state “tend to commit more serious crimes, are more likely to be classified as dangerous and are 45 percent more likely to be gang members.”

His findings were based on newly released data on all prisoners who entered the Arizona state prison system from January 1985 through June 2017.

Cato says Lott’s widely cited report overstates the extent of illegals’ crimes. The libertarian policy shop, which persistently spins numbers in defense of illegal immigrants, asserts that government data used by the researcher were off by roughly 10 percent.

Averring that some official reports may blur illegal-legal categories, Lott responded, “Let’s assume [Cato’s] criticism is correct and that the breakdown is only about 90 percent correct.”

“We estimated that undocumented immigrants accounted for 11.8 percent of prisoner convictions in Arizona, and that they make up about 4.8 percent of the population. If 10.5 percent of the people that we have listed as undocumented immigrants are actually documented immigrants or temporary visa holders, that reduces undocumented immigrants’ share of convictions leading to incarceration from 11.8 percent to 10.6 percent.”

“That would still imply an undocumented immigrant conviction rate that is 121 percent higher than their share of the population,” Lott says.

Further, Lott adds, “So let’s be cautious and assume that rather than 10.5 percent, the reduction should be 21 percent. Undocumented immigrants would still make up 9.32 percent of convictions and their share of convictions would still be 94 percent greater than their share of the population.”

By lazily lumping legal and illegal immigrants together, Cato researchers and others mute significant differences between the two groups. Immigration enthusiasts leverage such generalizations to make the specious claim that “immigrants” are more law-abiding than U.S.-born citizens.

Lott notes, “Just as undocumented immigrants are more likely to be criminals, documented immigrants tend to be very law-abiding. The results here also show that legal Hispanics are more law-abiding than the average Arizonan. The perception that Hispanics are more likely to be criminals arises from not distinguishing between legal and illegal Hispanics.”

“There are dramatic differences between in the criminal histories of convicts who are U.S. citizens and undocumented immigrants,” Lott asserts.

His study found that young convicts are especially likely to be undocumented immigrants.

“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,” Lott said. “These undocumented immigrants also tend to commit more serious crimes.”

Among that criminal cohort, Lott found “DACA (Deferred Action for Childhood Arrivals) age-eligible undocumented immigrants (so-called “DREAMers”) are 250 percent more likely to be convicted of crimes than their share of the population.”