As lawmakers debate loosening gun restrictions and expanding civilian use of deadly force against looters, a new 41-state study asks how “stand your ground” laws might affect homicide rates.

“Stand your ground” laws, also known as “shoot first" laws, permit people to use deadly force in self-defense as a first resort, replacing the common law principle of a “duty to retreat" and of using deadly force as a last resort. 

The JAMA Network Open paper links “stand your ground” laws with an 8% to 11% increase in homicides nationally.

Patterns varied by state.

Rates topped 10% in the South, where additional monthly homicides equaled the annual murder rates of many European countries.

Arizona saw fluctuations in its homicide rate, but the pattern did not indicate a link to its 2006 “stand your ground” law. The authors did not find such associations in any western state. 

Nowhere in the U.S. did such laws reduce homicides.

In an email, lead author and University of Oxford postdoc Michelle Degli Esposti said a state’s cultural norms can play a role in how such laws play out.

"The South has been shown to have a stronger cultural ideology that endorses the use of self-protective violence for maintaining 'honor' compared to other regions in the U.S.,” she said. 

Degli Esposti added that understanding the context in which the laws were introduced — a focused media and lobbying blitz, for example — may be key to understanding why states respond differently to such laws.

Existing firearm laws and gun availability likely also play a role.