In Texas, the association between marijuana and crime goes back more than a century. One hundred years ago, the state made marijuana use illegal, and it remains that way both for recreational and medical purposes today.

Some have argued legalization poses a threat to public health and safety. But new research led by UT Dallas published this month in the journal PLoS One shows no rise in crime rates following medical marijuana legalization and in fact, a possible reduction in homicide and assault rates.

The KERA radio story.

Robert G. Morris, associate professor of criminology and director of the Center for Crime & Justice Studies at UT Dallas conducted the study.

Main Medical Marijuana Legalization Fears:

1. If you legalize marijuana there is more available in the community and if people use marijuana more they’re more likely to use other drugs associated with crime. The “gateway” theory.

2. If medical marijuana is legalized, there will be dispensaries that could be the potential targets of crime, either attempts to steal the product or cash.

[More from KERA News: Nearly 100 Years After Marijuana Was Made Illegal In Texas, Fight To Legalize Gets Stronger]

The Findings:

“The main finding was that there was no increase in crime following legalization of marijuana for medical purposes,” Morris says, “And in fact some models suggest that reductions occurred for crimes including homicide and assault.”

You can read the full study in the journal PLoS One.

Why There Might Be A Reduction In Crime:

One of the arguments, Morris says, has to do with alcohol use.

“Some studies have shown when medical marijuana becomes available legally we have reductions in alcohol misuse, and since we have an association between alcohol misuse and crime, when people substitute the marijuana for the alcohol the crime that would have followed declines.”

Morris plans to conduct more research to study the effect on crime following the legalization of recreational use of marijuana in the states of Colorado and Washington.