This article originally appeared in the Chicago Tribune on Wednesday, January 16, 2019.

By Nina Vinik, Program Director, Gun Violence Prevention & Justice Reform

Last week, a 25-year-old woman was standing at a bus stop before dawn in the Fernwood neighborhood on Chicago’s Far South Side when she was approached by a teen who attempted to rob her with a gun. Instead, the woman, a concealed carry permit holder, pulled out her own gun and shot and killed the 19-year-old.

On its face, this story may seem to make the case for the merits of concealed carry as a method of self-protection, especially for people living in high-crime neighborhoods. But the fact is that this scenario is an outlier. It is extremely rare for a legal gun owner to use a gun successfully in self-defense.

A 2015 Harvard study analyzing data from the National Crime Victimization Surveys found that self-defense gun use is rare — victims use guns in less than 1 percent of contact crimes. That same year, there were more than 9,000 criminal homicides involving a gun, compared with just 265 justifiable homicides involving a private citizen using a firearm, according to the Violence Policy Center. This amounts to about 34 criminal homicides for every one justifiable homicide involving a gun.

In recent years, many states have relaxed their concealed carry laws, on the theory that concealed-gun carriers deter crime. But there is no credible evidence that permissive laws prevent or deter crime. In an analysis of states with right-to-carry laws, Stanford researcher John Donohue and colleagues found that states that passed right-to-carry laws experienced 13 to 15 percent higher aggregate violent crime rates, over a period of 10 years, than comparable states.

The researchers identified several reasons why permissive concealed carry actually increases violent crime. There is ample evidence of gun owners feeling overconfident about their ability to use guns responsibly, leading to riskier behavior and outcomes ranging from criminal misconduct and gun accidents to lost or stolen guns. Right-to-carry laws also normalize the practice of carrying guns, making it harder for the police to know who is and who is not allowed to possess guns in public.

Examples abound of concealed-gun carriers attempting — and failing — to thwart crimes, often with deadly consequences. Last year in Portland, Ore., Portland State University campus police officers arrived as a “good Samaritan” with a concealed carry permit was trying to break up a fight. The police saw the gun held by the permit holder — a Navy veteran, postal worker and father of three — and in the confusion shot and killed him. In 2016 in Arlington, Texas, a man in a domestic dispute shot at a woman and then tried to drive off. When he was confronted by a permit holder, the shooter slapped the permit holder’s gun out of his hand and then killed him with a shot to the head. In 2014, a permit holder pursued a man who had robbed a phone store in south suburban Crestwood, firing at the fleeing suspect. A police officer pursuing the suspect had to duck for cover, not knowing where the shots were coming from.

Although the Chicago case involved a female concealed carry holder, women are at greater risk when guns are in the home. A 2003 study published in the Annals of Emergency Medicine journal found that women living in a household with a gun are nearly three times more likely to be murdered than women with no gun in the home. In 2015, women were over 50 times more likely to be murdered by a man with a gun than to use it to kill a man in self-defense, according to the Violence Policy Center. Guns in the home also heighten the risk of suicide, and accidental gun injuries and deaths.

With gun-related deaths topping nearly 40,000 in 2017 in the U.S., according to federal data, anyone who is seriously considering carrying a gun for self-protection would do well to consider the evidence.