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Statewide Prevalence of Gun Ownership Tied to Police Use of Lethal Force

Police use of lethal force in the United States has triggered public scrutiny of violent interactions between police and citizens. Past research has focused on whether race and levels of violence contribute to this phenomenon. A new study expands on prior research by examining the impact of the availability of firearms. It finds a pronounced positive relationship between statewide prevalence of gun ownership by citizens and police use of lethal force.

The study, by a researcher at Carnegie Mellon University, appears in The Annals of the American Academy of Political and Social Science.

“One consequence of higher rates of firearm prevalence in a state may lead to a greater frequency of police encountering individuals who are armed or suspected to be armed, which in turn results in a greater frequency of police using lethal force,” explains Daniel S. Nagin, professor of public policy and statistics at Carnegie Mellon University's Heinz College, the author of the study.

Nagin based his work on data collected in a Washington Post inventory of police use of lethal force nationwide from 2015 to 2018. As a first step in his analysis, Nagin confirmed a positive correlation across all 50 states between the prevalence of firearms and percentage of lethal encounters in which the victim possessed a firearm.

Nagin’s analysis identified a pronounced, highly significant association between the statewide rate at which police use lethal force and the statewide prevalence of firearms. The association could be interpreted as reflecting a causal effect of the availability of firearms on police use of lethal force, Nagin suggests.

Because the data measured only violent encounters with the police that ended in death, not all violent encounters, taking account of proximity of trauma services is important. The analysis found that access to trauma centers, measured by the percentage of a state’s population living within one hour of a Level I trauma center (one that can provide total care for every aspect of injury) or a Level II trauma center (one that has 24-hour immediate coverage by general surgeons and specialists), was associated with lower rates of deaths of individuals who have violent encounters with police; the finding supports the importance of rapid access to emergency medical care.

“One of the policy implications of the study’s findings is that we should reduce the availability of firearms to active offenders and individuals at high risk of offending,” Nagin suggests. “Among the policies intended to do this are universal background checks and training police to use de-escalation skills.”


Summarized from an article in The Annals of the American Academy of Political and Social Science, Firearm Availability and Police Use of Lethal Force by Nagin, DL (Carnegie Mellon University). Copyright 2019. All rights reserved. 

About Carnegie Mellon University's Heinz College of Information Systems and Public Policy
The Heinz College of Information Systems and Public Policy is home to two internationally recognized graduate-level institutions at Carnegie Mellon University: the School of Information Systems and Management and the School of Public Policy and Management. This unique colocation combined with its expertise in analytics set Heinz College apart in the areas of cybersecurity, health care, the future of work, smart cities, and arts & entertainment. In 2016, INFORMS named Heinz College the #1 academic program for Analytics Education. For more information, please visit