Which specific gun control measures are most correlated with reductions in mass shooting incidents in the US?
Executive summary
The strongest, most consistent empirical signals point to comprehensive firearm purchaser-licensing laws (including background checks and waiting periods), and targeted “extreme risk” or red-flag laws as the policies most correlated with reductions in mass-shooting incidents and deaths; assault‑weapon and high‑capacity‑magazine bans show a statistically significant but smaller and more uncertain association, while evidence for many other policies is mixed and methodologically limited [1] [2] [3]. Major policy‑rating groups and systematic reviews agree that states with a package of stronger gun-safety laws experience fewer gun deaths overall, though researchers warn of gaps and confounders in the mass‑shooting literature [4] [5] [3].
1. Purchaser licensing and comprehensive background checks: the clearest empirical association
A growing body of work highlights firearm purchaser‑licensing regimes—laws that require prospective buyers to obtain a license after background checks, training, and sometimes safety demonstrations—as among the most potent correlates of fewer mass‑shooting events; a 2020 study cited by Johns Hopkins found licensing laws associated with roughly 56% fewer mass‑shooting incidents and 67% fewer victims on average, and other research links purchaser licensing to lower urban gun homicide rates [1]. Policy advocates and public‑health centers, including Johns Hopkins and Giffords, therefore prioritize licensing and universal background checks as foundational measures associated with lower gun‑death outcomes across states [1] [4].
2. Extreme Risk Protection Orders (red‑flag laws) and waiting periods: targeted risk reduction
Extreme Risk Protection Orders, which temporarily remove firearms from people judged to be at acute risk, are promoted as critical tools by advocacy organizations and state policy compendia and are repeatedly recommended as part of a core package that correlates with fewer firearm deaths [5] [4]. RAND’s synthesis of the evidence finds some policies—like waiting periods—that have robust evidence of reducing firearm suicides and therefore overall gun deaths, and these targeted measures plausibly reduce the immediate risk profile that sometimes precedes mass‑attack behavior [6] [3].
3. Assault‑weapon and high‑capacity magazine bans: measurable but smaller effects and methodological caveats
Analyses of state bans on assault weapons and high‑capacity magazines suggest statistically significant reductions in mass‑shooting death rates—one RAND‑summarized study estimated deaths fell to about 55% of expected levels under bans—but results are smaller and less certain than those for purchaser licensing, and studies can be sensitive to model specification, timing of bans, and confounding federal policies [2]. RAND and other reviewers caution that methodological limitations—small numbers of events, serial correlation in panel data, and variation in definitions—make precise estimates fragile and warrant cautious interpretation [2] [3].
4. The package effect and state‑level contrasts: restrictive states see fewer mass shootings
Cross‑state time‑series research and numerous policy scorecards consistently show that states with more restrictive, comprehensive gun‑safety regimes have lower rates of mass shootings and gun deaths compared with permissive states; the BMJ cross‑sectional time‑series work and multiple advocacy scorecards find correlations between restrictiveness and reduced mass‑shooting incidence [7] [4] [5]. Analysts describe this as a package effect: combinations of purchaser licensing, background checks, safe‑storage rules, ERPOs, and limits on carry produce clearer associations than any single, isolated law [5] [4].
5. What the evidence does not (yet) conclusively show and why caution is needed
Systematic reviews from RAND and others stress important gaps: there are few high‑power studies for many laws, definitions of “mass shooting” vary, and causal attribution is complicated by low event counts and unobserved confounders, so claims about single‑law silver bullets are not supported by robust, unanimous evidence [3] [2]. RAND’s program explicitly notes which policies have stronger vs. weaker evidence and flags that some findings (for example, assault‑weapon bans) are suggestive but uncertain because of methodological constraints [6] [2].
6. Practical takeaway: focus on licensing, ERPOs, waiting periods, and packages rather than a single law
The reporting and peer‑reviewed syntheses converge on a practical policy inference: comprehensive purchaser‑licensing regimes—bundled with background checks, waiting periods, and extreme‑risk laws—show the clearest, most substantial correlations with fewer mass‑shooting incidents and victims, while assault‑weapon and magazine bans likely help but with more modest, less certain effects; researchers and advocates caution that multi‑law packages and better data are essential to sharpen causal claims [1] [5] [2] [3].