Do Gun Laws Stop Mass Shootings? Science Explains

The Scientific Approach to Mass Shootings

This episode of Science Versus investigates the efficacy of common policy proposals aimed at curbing mass shootings in the United States, moving past political rhetoric to evaluate what the available data suggests.

Gun Bans and High-Capacity Magazines

While banning assault weapons is a common legislative goal, research suggests that the rifles themselves may not be the primary factor. Instead, the capacity to inflict mass casualties is often tied to high-capacity magazines.

• Studies indicate that bans on assault weapons have had mixed results in reducing mass shootings.
• Use of high-capacity magazines is directly correlated with significantly higher casualty counts.
• Stricter international models, such as Australia’s, involved broader bans and mandatory confiscation, policies viewed as politically challenging in the U.S.

School Security and Armed Defense

Proponents often argue that more armed presence acts as a deterrent, but empirical data tells a more complex story.

• Analysis of school shootings found that shootings with armed guards on site saw higher casualty rates than those without, potentially because perpetrators plan around known security measures.
• Surveys consistently show that teachers are largely opposed to being armed.
• Armed civilian presence has a negligible statistical impact on stopping active shooters.

The Role of Mental Health and Suicidality

"The vast majority of people with mental illness... are not violent."

Distinctions must be made between general mental health struggles and the specific factors driving mass shootings.

• Only a small minority (~11%) of mass shooters are primarily motivated by psychosis.
• Approximately 70% of shooters are suicidal, framing these events as "angry suicides" resulting from a grievance-based crisis.
• Media sensationalism, including the publication of manifestos or triumphantly reporting the shooter's name, often fuels copycat behavior.

Red Flag Laws

These laws offer a temporary legal mechanism to remove firearms from individuals exhibiting clear warning signs.

• Research shows these laws effectively prevent suicides and have intercepted individuals threatening to commit mass shootings.
• "Leakage"—where threats are revealed to others—occurs in about half of cases, providing a window for intervention via red flag laws.

Conclusion

There is no single solution according to the "Swiss cheese" model of policy: multiple imperfect layers of prevention are required to effectively cover the holes in public safety.