Which specific state gun laws (background checks, red‑flag laws, safe storage) have the strongest evidence for reducing firearm homicides or suicides?
Executive summary
Strong, multi-study evidence ties universal background checks and broader sales/transfer regulations to reductions in firearm homicides and suicides, while policies that remove firearms from high‑risk individuals — commonly called red‑flag or extreme risk laws — show promising reductions in suicide with emerging evidence on homicides; safe‑storage and child‑access prevention laws have the strongest, most consistent evidence for lowering firearm suicide and unintentional child deaths but weaker or mixed findings for homicides [1] [2] [3] [4].
1. Universal background checks: a repeatedly observed difference‑maker
Multiple national analyses and systematic syntheses report that laws requiring background checks for all gun sales or tighter regulation of sales and transfers correlate with lower firearm homicide and suicide rates; a JAMA‑linked county‑level analysis found states with stronger firearm law scores had lower firearm homicide and suicide rates, and other work singled out background checks as among the law types most consistently associated with reduced homicides [5] [6] [3]. Configurational analysis across states also identified universal background checks as one of the distinct pathways sufficient for low firearm suicide rates and as a common element linked to lower homicide in some solution sets [1]. RAND rated evidence for background checks as “moderate” for reducing homicides and firearm homicides, reflecting multiple observational studies but also noting research gaps [2].
2. Red‑flag laws / firearm removal during crisis: promising for suicide, mixed for homicide but plausible
Policies that authorize temporary firearm removal from people deemed an imminent risk (extreme risk protection orders, ERPOs, or similar) have been associated in several studies with reductions in suicide; a multi‑state estimate suggested each ERPO issuance can prevent lives, and international and U.S. “removal” law analyses report decreases in firearm suicides after implementation [4] [7]. The evidence on homicides is less consistent and sometimes confounded by study design and implementation variability, and some evaluations show modest or uncertain effects on interpersonal violence, so conclusions for homicide remain tentative [4] [3].
3. Safe storage and child‑access prevention: strongest evidence for preventing youth suicide and unintentional deaths
Child‑access prevention (CAP) and safe‑storage laws score highly in systematic reviews: RAND classifies CAP laws among the policies with the strongest supportive evidence for reducing firearm self‑harm and unintentional injuries among youth [2]. Studies report notable drops in the proportion of suicides that involve firearms where lock/secure storage laws exist, and pediatric research finds safe‑storage laws and waiting periods associated with lower child suicide rates [8] [9]. Evidence tying safe‑storage directly to reduced adult homicides is weaker, but the benefits for reducing youth suicides and accidental shootings are consistent [2] [8].
4. Licensing, permitting, waiting periods and age limits: effective especially for suicide and youth outcomes
State handgun purchaser licensing and permitting laws — exemplified by Connecticut’s 1995 law — have been linked to substantial reductions in both firearm homicides and suicides in longitudinal studies, and waiting‑period laws have moderate evidence for reducing suicides and total homicides [7] [2] [3]. Minimum‑age purchase laws show supportive evidence for reducing suicides among young people, though most studies evaluate narrow age bands and therefore have limitations [2].
5. Homicides are more complex — law strength helps but social determinants matter
While composite measures of stronger gun‑law regimes generally correlate with fewer firearm homicides, studies repeatedly emphasize that homicide reductions are more sensitive to local sociodemographic factors (poverty, unemployment, segregation) and interstate spillovers from neighboring states’ laws, meaning single law effects on homicide are often smaller and context‑dependent [3] [5] [6]. RAND and multiple cross‑state studies caution that evidence quality varies and that policies are often evaluated in bundles, complicating causal attribution [2] [6].
6. What the evidence collectively recommends
The strongest and most consistent policy signals across the literature support universal background checks and robust sales/transfer regulations for lowering homicide and suicide at the population level, ERPOs and removal laws for preventing suicide (with growing but not definitive homicide evidence), and child‑access/safe‑storage laws for reducing youth suicide and unintentional firearm deaths [6] [1] [4] [2]. Studies and syntheses repeatedly stress implementation quality, interstate spillover, and socioeconomic drivers as crucial modifiers of any law’s impact [5] [3] [6].