Background In the United States, every day, close to 30 people die in alcohol-impaired related crashes. Given the known role of alcohol in traffic injuries, we assessed the impact of drink special laws on alcohol- and non-alcohol-related fatal motor vehicle crash rates.

Methods We performed a synthetic control analysis of US data from 1982 to 2017. We used publicly available data to evaluate the effects of implementing any drink special law at the state-level during the study period on fatality rates per 100 million vehicle-miles of travel. We used an enhanced version of the SC method for the analysis of multiple treated units.

Results Overall, treated states with any drink special law reduced alcohol-related fatal crashes per 100 million VMT by 0.01 (p-value = 0.84) in year one, 0.10 (p-value = 0.14) in year three, 0.07 (p-value = 0.28) in year five, and 0.16 (p-value = 0.01) in year 10 post-implementation compared to the synthetic control trend. Implementation of any drink special law also produced reductions of non-alcohol-related fatal crashes per 100 million VMT by 0.19 (p-value = 0.11) in year one, 0.24 (p-value = 0.03) in year three, 0.25 (p-value = 0.00) in year five, and 0.18 (p-value = 0.00) in year 10 compared to the synthetic control trend. Findings for the number of laws implemented and each drink special laws were mixed.

Conclusions Drink special laws appeared to be associated with larger reductions of non-alcohol-related fatal crashes but no with the hypothesized target population, the alcohol-related fatal crashes.