2025 Theses Doctoral

The Role of Defensive Gun Use in Injury Prevention: Insights from 50 years of U.S. Crime Data

Jorgenson, Erik Scott

Understanding the effectiveness and contexts of defensive gun use (DGU) in preventing injury during violent incidents is critical for informing public safety policies and injury prevention practices. This dissertation addresses critical gaps in the literature by (i) systematically examining risk factors associated with interpersonal violence involving DGU, and (ii) evaluating the efficacy of DGU – and defensive weapon use (DWU) more broadly – in mitigating victim injuries across varying offender scenarios and historical contexts.

A comprehensive scoping review of studies published from 1946 to 2024 identified both static (e.g., substance use history, prior victimization) and dynamic risk factors (e.g., offender weapon presence, acute intoxication) associated with DGU incidents. This review underscored the necessity for nuanced definitions and improved categorizations of risk factors to enhance the reliability of future empirical investigations.

Empirical analyses utilized National Crime Victimization Survey (NCVS) data spanning 1973-2022, employing advanced statistical methodologies including Bayesian Additive Regression Trees (BART) and Guided Bayesian Adjustment for Confounding (GBAC) to model the relationship between DGU and injury to defensive gun users. Findings revealed that, compared to forcefully resisting assailants without the use of guns, DGU significantly reduced victim injury risk in incidents involving unarmed offenders (approximately 24-26 percentage point decrease compared to non-firearm defensive actions). However, these protective effects were substantially attenuated or nullified when offenders were armed, particularly with guns. Additionally, temporal analyses illustrated minimal shifts in effectiveness correlated with macro-level changes, such as increased gun ownership post-2008, and minor variations between urban and rural contexts.

In conclusion, this dissertation highlights that the protective utility of firearms for self-defense is highly context-dependent, significantly effective primarily against unarmed offenders. Future research and policy initiatives must consider detailed situational dynamics and evolving societal factors to enhance the effectiveness of defensive actions and public safety strategies.