1. Where there are more guns there is more homicide (literature review)

Our review of the academic literature found that a broad array of evidence indicates that gun availability is a risk factor for homicide, both in the United States and across high-income countries. Case-control studies, ecological time-series and cross-sectional studies indicate that in homes, cities, states and regions in the U.S., where there are more guns, both men and women are at a higher risk for homicide, particularly firearm homicide.

Hepburn, Lisa; Hemenway, David. Firearm availability and homicide: A review of the literature. Aggression and Violent Behavior: A Review Journal. 2004; 9:417-40.

2. Across high-income nations, more guns = more homicide

We analyzed the relationship between homicide and gun availability using data from 26 developed countries from the early 1990s. We found that across developed countries, where guns are more available, there are more homicides. These results often hold even when the United States is excluded.

Hemenway, David; Miller, Matthew. Firearm availability and homicide rates across 26 high income countries. Journal of Trauma. 2000; 49:985-88.

3. Across states, more guns = more homicide

Using a validated proxy for firearm ownership, we analyzed the relationship between firearm availability and homicide across 50 states over a ten-year period (1988-1997).

After controlling for poverty and urbanization, for every age group, people in states with many guns have elevated rates of homicide, particularly firearm homicide.

Miller, Matthew; Azrael, Deborah; Hemenway, David. Household firearm ownership levels and homicide rates across U.S. regions and states, 1988-1997. American Journal of Public Health. 2002; 92:1988-1993.

4. Across states, more guns = more homicide (2)

Using survey data on rates of household gun ownership, we examined the association between gun availability and homicide across states, 2001-2003. We found that states with higher levels of household gun ownership had higher rates of firearm homicide and overall homicide. This relationship held for both genders and all age groups, after accounting for rates of aggravated assault, robbery, unemployment, urbanization, alcohol consumption, and resource deprivation (e.g., poverty). There was no association between gun prevalence and non-firearm homicide.

Miller, Matthew; Azrael, Deborah; Hemenway, David. State-level homicide victimization rates in the U.S. in relation to survey measures of household firearm ownership, 2001-2003. Social Science and Medicine. 2007; 64:656-64.

5. A summary of the evidence on guns and violent death

This book chapter summarizes the scientific literature on the relationship between gun prevalence (levels of household gun ownership) and suicide, homicide and unintentional firearm death and concludes that where there are higher levels of gun ownership, there are more gun suicides and more total suicides, more gun homicides and more total homicides, and more accidental gun deaths.

This is the first chapter in the book and provides and up-to-date and readable summary of the literature on the relationship between guns and death. It also adds to the literature by using the National Violent Death Reporting System data to show where (home or away) the shootings occurred. Suicides for all age groups and homicides for children and aging adults most often occurred in their own home.

Miller M, Azrael D, Hemenway D. Firearms and violence death in the United States. In: Webster DW, Vernick JS, eds. Reducing Gun Violence in America. Baltimore MD: Johns Hopkins University Press, 2013.

6. More guns = more homicides of police

This article examines homicide rates of Law Enforcement Officers (LEOs) from 1996 to 2010. Differences in rates of homicides of LEOs across states are best explained not by differences in crime, but by differences in household gun ownership. In high gun states, LEOs are 3 times more likely to be murdered than LEOs working in low-gun states.

This article was cited by President Obama in a speech to a police association. This article will hopefully bring police further into the camp of those pushing for sensible gun laws.

Swedler DI, Simmons MM, Dominici F, Hemenway D. Firearm prevalence and homicides of law enforcement officers in the United States. American Journal of Public Health. 2015; 105:2042-48.