Road rage is an American pastime. Nearly 80 percent of motorists admitted to at least one instance of aggressive driving in the past year, according to a 2016 study. A generation ago, drivers confronting each other over a traffic squabble could assume their quarrel would end with strong words or, at worst, a black eye. But in 2013, after one car tailgated another, two men in Ionia, Michigan, stopped in a parking lot to resolve their dispute. Instead of duking it out, they pulled out guns and shot each other. Both men legally carried a concealed weapon; both died in the hospital. (In states without a “right to carry,” the law usually requires people to store their firearms in the trunks of their cars.)

In 1997, researchers John Lott and David Mustard asserted that more guns meant less crime; it was an influential argument that likely contributed to states passing right-to-carry laws. Ever since, there’s been a debate over the effects of this legislation on violent crime.

But with an updated paper by legal scholars John Donohue and Abhay Aneja and economist Kyle Weber, there’s a new consensus: Right-to-carry laws actually increase the rate of violent crime. Ten years after a state passes a right-to-carry law, violent crime—which includes murder, manslaughter, forcible rape, robbery, and aggravated assault—will be 13 to 15 percent higher than if the state had done nothing.

What makes this new report so convincing? First, there’s simply a lot more experience with right-to-carry laws: 33 states adopted such legislation between 1981 and 2007. There’s also a lot more data: The researchers were able to track crime statistics until 2014.

Starting in the early 1990s, violent crime plummeted across the United States. That reduction has masked the effects of right-to-carry laws, but the states that implemented them showed a smaller decrease in violent crime than the ones that didn’t. By itself, this isn’t sufficient evidence, since there could be other factors involved. But the study’s authors used a variety of controls to compare the two sets of states, and they found that the increase in violent crime holds. Interestingly, with the additional data, they found that even the methods of researchers like Lott and Mustard confirm this rise.

The authors of this new paper have taken advantage of cutting-edge statistical techniques. They constructed synthetic control groups for states and used what’s known as a LASSO analysis to pick the best variables for comparison. The important thing to know about these methods is that, no matter the relative trade-offs of the statistical tool, the findings were consistent: When states passed right-to-carry laws, violent crime ended up higher than it would have been otherwise.

The report also found that a right to carry has no deterrent effect on property crimes. (Indeed, in some of the calculations, such crimes increased.) This lack of deterrence isn’t surprising, given that victims of violent crimes fail to defend themselves with a gun 99.2 percent of the time. Using reasonable estimates of the relationship between incarceration and crime—that for every 10 percent increase in incarceration, there’s a 1.5 percent decrease in crime—the researchers estimate that the average right-to-carry state would have to double its prison population to counter the effects of this legislation.

What causes this rise? The authors note several channels, including road rage, bar fights, and other heated interactions that once would have ended in insults or a fistfight, but that now suddenly turn deadly. Also, people who carry guns outside their homes have their firearms stolen at a rate of more than 1 percent a year, making these concealed-carry permit holders a nice source of guns for would-be criminals.

This research comes at a perfect time. A bill that passed the House in December and is currently before the Senate Judiciary Committee would allow people with a concealed-carry permit in a given state to carry their firearms in the rest of the country. On April 19, the International Association of Chiefs of Police, which includes the heads of 18,000 departments, sent a letter to Congress opposing the law. Now there is overwhelming evidence to back up their claims: Right-to-carry laws only lead to more violence.