This article first appeared on the UC Berkeley Law School website on 8/13/2019

Mental illness. Video games. The Internet. These are excuses offered by the U.S. President and his supporters for a scourge of mass killings. But five decades of empirical research by preeminent criminal law expert Professor Franklin Zimring tell a different story: The core of our country’s deadly violence is access to weaponry.

An estimated three-hundred million guns are cached throughout America’s households: handguns, rifles, assault weapons. The idea that “guns don’t kill people—people kill people,” promoted by gun advocates, skirts the issue.

“Does the availability of guns increase the death rate from assault? Of course, it does,” Zimring said. “Trying to reduce death totals without discussing guns” belies logic and “ignores risks to public health.” 

Seminal research

In the groundbreaking 1997 book “Crime Is Not the Problem: Lethal Violence in America,” Zimring and his co-author found that U.S. crime rates were similar to—even lower than—most other developed countries. But when it comes to lethal violence, the U.S. far outpaces the rest: a toxic brew of permissive gun laws and weapons on the ground.

Other contributing factors come into play but to lesser degrees.

“There’s an extraordinary amount of behavioral research into the significant causes of lethal violence,” Zimring said. “Guns top the list. It’s no secret—and it isn’t something that the current president of the United States doesn’t know. It’s just something that he doesn’t want to accept.”

The proliferation of high-caliber assault weapons means the outcomes are even more lethal.

In a seminal 1972 study of crime in Chicago, Zimring looked at firearm caliber: Did bullet size determine the outcome? Absolutely. The .38 caliber attacks were more than twice as deadly as the .22 caliber attacks. A 2018 study of assaults in Boston replicated Zimring’s findings. 

Curbing gun violence

Zimring has recommended stronger gun laws for decades, including the licensing and registration of handgun owners and their weapons. He said “closing the loopholes” on universal background checks at the federal level is one of the most important legal reforms. Although not closely tied to mass shooting episodes, “They are the best bet for curbing high-risk user access.” 

A 1994 assault weapons ban, designed to reduce the number of deadly mass shootings nationwide, restricted civilian ownership of new military-grade weapons. The result? Gun massacres dropped significantly during the ban and then skyrocketed after it expired in 2004. 

The U.S. House has passed a new assault weapons ban—as well as a bill requiring universal background checks—but both are stalled in the Republican-controlled Senate.

In the wake of congressional inaction, states have enacted their own laws. A dozen have passed extreme risk protection laws –or “red flag” laws—that permit confiscating guns from at-risk individuals. Some red states have weakened their gun laws, while California is the first state to require background checks for every ammunition purchase.