The Science of Gun Policy: A Critical Synthesis of Research Evidence on the Effects of Gun Policies in the United States (Fourth Edition)

List of Key Chapter Titles

1. Introduction and Research Methods
2. Policies Regulating Legal Gun Owners, Purchasers, or Possessors
3. Policies Regulating Gun Sales and Transfers
4. Policies Regulating the Legal Use, Storage, or Carrying of Firearms
5. Impact of Minimum Age Requirement Policies
6. Gun Prohibition Policies Related to Mental Illness
7. Gun Prohibition Policies Related to Domestic Violence
8. Policies Prohibiting Possession and Requiring Firearm Surrender
9. Extreme Risk Protection Order Policies
10. Empirical Effects of Background Check Policies
11. Impact of Waiting Period Policies on Suicide and Homicide
12. Summary of Research Findings and Policy Recommendations

Document Introduction

The formulation of U.S. gun policy has long been constrained by a lack of reliable empirical evidence, making it difficult to balance Second Amendment rights, the public interest in gun ownership, and public health and safety concerns. To address this, the RAND Corporation launched the "Gun Policy in America" initiative in 2016, aiming to provide policymakers and the public with an objective basis for decision-making through transparent, unbiased research synthesis. This report, as the fourth edition of this initiative, represents a significant update and expansion of previous research.

The report focuses on 18 categories of gun policies already implemented in some U.S. states, covering three core areas: regulating gun owner eligibility, regulating gun sales and transfer processes, and regulating gun use and storage behaviors. The research team employed rigorous systematic review methods, screening quasi-experimental studies published between January 1995 and February 2023. They conducted evidence strength ratings and effect analyses centered on eight outcome indicators: suicide, violent crime, unintentional injuries and deaths, mass shootings, police shootings, defensive gun use, hunting and recreation, and the gun industry.

Methodologically, the report established a standardized evidence strength assessment system (no studies, inconclusive evidence, limited evidence, moderate evidence, supportive evidence). It ensured the rigor of causal inference through time-series data and control group designs, while also critically examining methodological flaws in the research. All analyses followed a pre-registered study protocol to ensure transparency and reproducibility of the research process and avoid outcome bias.

Key findings show that stronger empirical support has formed for the effects of some policies: Child Access Prevention (CAP) laws effectively reduce firearm suicides, unintentional injuries, and homicides among youth; "Stand Your Ground" laws and "Shall-Issue" laws are associated with increased homicide rates; background checks, waiting periods, and other policies have positive effects on reducing suicide and homicide. Simultaneously, the report also points out that research remains extremely scarce in areas such as defensive gun use, hunting and recreation, and the gun industry, and the long-term impacts and interactive effects of most policies have not been fully validated.

The report ultimately proposes two core types of recommendations: first, policy optimization suggestions based on existing evidence, including promoting Child Access Prevention laws, repealing "Stand Your Ground" laws, strengthening background checks, etc.; second, research improvement suggestions targeting evidence gaps, covering areas such as expanding research funding, improving data collection systems, and optimizing research methodologies, providing an action framework for building a more robust evidence base for gun policy.