Supporters insist that allowing people to legally carry concealed handguns reduces crime, but that has not been the result in at least four states that have tried it, including Texas, according to a newly published academic study led by a Texas A&M researcher.

The study published in the Journal of Criminology looked at the connection between crime rates and concealed handgun permits for each county in Michigan, Pennsylvania, Florida and Texas.

Researchers used two sources of data from 1998 to 2010: concealed handgun license information and arrest data from Uniform Crime Reports, which the FBI compiles nationwide to gauge arrests for serious crimes including homicide, rape, robbery, aggravated assault, burglary, theft and arson.

Overall, they found no connection between allowing concealed weapons and crime rates, which are trending downward nationwide.

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“The idea that concealed handguns lead to less crime is at the center of much firearms legislation, but the science behind that conclusion has been murky,” said study lead Charles D. Phillips, an emeritus regents professor at the Texas A&M Health Science Center School of Public Health, in a statement. “The results have been so inconclusive that the National Academy of Sciences in 2004 called for a new approaches to studying the issue, which is what we’ve done with this research.”

The study comes after Texas lawmakers decided to allow concealed handguns on college campuses. Supporters argued that concealed carry in general prevents crime, while opponents say it can amplify tense situations and create violent ends for disputes. The campus-carry legislation that Gov. Greg Abbott signed into law in June begins to take effect next year.

While previous studies looked at crime rates before and after concealed carry legislation passed in states, the A&M study focused on county-level data while gauging change in crime rates over time.

The lack of impact on crime rates sounds right, said state Rep. Garnet Coleman, a Houston Democrat who chairs the House County Affairs Committee, which tackles criminal justice issues.

“People who commit crimes are less likely to go through that background check,” he said.  It’s also unlikely that a concealed handgun license holder would be in the right place at the right time to stop a crime, Coleman said.

The academic community isn't united on the issue, though. Two 2014 studies reach competing conclusions: one finding that right-to-carry laws lead to an increase in violent crimes, and another concluding right-to-carry laws led to a decrease in the murder rate nationwide.

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“Studies are studies,” said Larry Arnold, a board member of the Texas Concealed Handgun Association, which promotes Second Amendment rights and education about gun legislation. Since concealed carry legislation began taking effect more than 35 years ago, he said, opponents have predicted “blood in the streets,” “fender benders turning into fire fights” and “more people with guns would shoot out instead of talk it out.”

But they were wrong, and concealed handgun license holders are less likely than other groups to be involved in a crime, Arnold said, “so I think that’s a pretty good record.”

The study also reports that the presence of gun dealers — not fear of being victimized — most often prompts people to obtain concealed carry permits.

Disclosure: Texas A&M University is a corporate sponsor of The Texas Tribune. A complete list of Tribune donors and sponsors can be viewed here.