Proceedings of the National Academy of Sciences – Waiting periods and gun deaths. Michael Luca, September 21, 2017. doi: 10.1073/pnas.1619896114

“Each year, more than 33,000 gun-related deaths occur in the United States. Waiting period laws have the potential to deter gun violence by delaying the acquisition of a firearm. Michael Luca et al. compared the changes in the number of firearm-related deaths in states that enacted handgun waiting periods to the changes in the number of firearm-related deaths in states without waiting period laws from 1970 to 2014; 44 states including Washington, DC, had waiting periods at some point during this period. The authors find that waiting periods were associated with approximately 36 fewer gun homicides per year in a state with an average number of gun deaths. Waiting periods also were associated with 22–35 fewer gun suicides per year in a state with an average number of gun deaths. Furthermore, the authors conducted a supplemental analysis of the period from 1990 to 1998, during which a federal law—the Brady Act—required 19 states to adopt new handgun waiting periods. The authors found that waiting periods enacted during this time were associated with approximately 39 fewer gun homicides and approximately 17 fewer gun suicides per year for a state with an average number of gun deaths. The authors suggest that the 17 states, including Washington, DC, that had waiting periods as of 2014, likely avoid approximately 750 gun homicides per year with waiting period laws, and that passing waiting period laws in the remaining states might prevent more than 900 additional US gun homicides per year. “