Here's how alcohol can help turn people into criminals

A new working paper by two economists at the University of Oregon investigates the relationship between alcohol consumption and criminality.

They examined a dataset containing all criminal charges filed in the state of Oregon between 1990 and 2012, focusing on a key question: How does a person's risk for criminality increase when they turn 21, the legal drinking age?

From age 19 to age 21, the risk of criminality dropped steadily. There were somewhere between 21,000 and 22,000 charges filed against people exactly 19 years old in the dataset, the economists found. That number fell to around 19,000 charges filed against people just shy of 21.

As soon as people turned 21, their likelihood of criminality spiked considerably. (The researchers didn't adjusted for population, but in an email co-author Glen Waddell noted that "population does not sharply change at 21.")

The number of charges filed against 21-year-olds was similar to the number for 19-year-olds. In other words, from a criminal justice standpoint, turning 21 is akin to turning back the clock to your late teens.

The mechanism by which this works is fairly obvious — access to alcohol increases dramatically at age 21. That brings more intoxication, and with it more aggressive, belligerent and criminally stupid behavior. As researchers Mark Kleiman, Jonathan Caulkins and Angela Hawken wrote in a book on drug policy in 2011, "there is a good deal of evidence showing an association between alcohol intoxication and violent crime."

The relationship between the drinking age and the observed boost in crime is just an association, not necessarily a causal one. But the University of Oregon's Waddell noted in an email that there aren't other plausible confounding factors that explain the crime spike. Kids in Oregon get drivers licenses at age 16, can drop out of school at age 17, and can vote and purchase handguns at age 18. There aren't other big developmental or legal milestones at age 21 that would explain the shift.

Beyond that, the association between alcohol use and criminality is well documented.

The Oregon economists dug into these numbers a bit deeper, teasing out which types of crime seem to jump at the 21 threshold, and which do not.

"DUI's, reckless driving, disorderly conduct, alcohol possession in parks, and selling to minors all increase with legal access to alcohol," they wrote.

More troubling, turning 21 brings an uptick in the likelihood of committing assault, especially for people with no prior criminal history. For assault, the increase at age 21 is 10 times larger among first-time offenders than it is among those who committed prior crimes. There's a similar disparity in charges for drunk driving, which are more likely to spike for those with no criminal record.

In other words, the researchers write, it is possible that "alcohol availability induces individuals into criminality, rather than increasing the criminality of those with established histories of violating the law."