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Accurate data about alcohol-impaired driving is critical for monitoring trends and for developing and evaluating effective programs to address the problem. All States and the District of Columbia report BACs for drivers in fatal crashes to NHTSA’s Fatality Analysis Reporting System. Each State has its own laws and guidelines for BAC testing, and the reporting levels vary from State to State. In 2021 BAC test results were known for 38% of all drivers involved in fatal crashes, including 59% of drivers who were killed and 21% of surviving drivers (NCSA, 2023c). Known BAC test results were highest in South Dakota (81%) and lowest in Mississippi (9%). Testing rates have decreased over the past decade. In 2012 BAC test results were known for 52% of all drivers involved in fatal crashes, including 75% of drivers who were killed and 31% of surviving drivers (NCSA, 2023c).

Casanova et al. (2012) examined State practices for BAC testing and reporting in fatal crashes. At that time, 25 U.S. States required testing for all (or nearly all) fatally injured drivers. In the remaining States, law enforcement officers need probable cause to request BAC tests. Testing rates were approximately 15% higher, on average, in mandatory testing States. However, some probable-cause States tested over 80% of fatally injured drivers. Hence, laws by themselves do not guarantee high testing rates—a State’s practices and procedures can be just as important for achieving high rates.

Casanova et al. (2012) also conducted case studies of 9 States that have maintained high BAC testing rates or improved their rates substantially. The report described how these States overcame obstacles and used creative strategies to increase testing rates. Overall, factors associated with high testing rates included clear responsibility and policy, standard procedures, inter-agency cooperation, dedicated staff, and strong BAC laws.

For an overview of available data sources on alcohol-impaired driving, data gaps and barriers, data access, and future data and surveillance needs, see the National Academies of Sciences, Engineering, and Medicine’s Getting to Zero Alcohol-Impaired Driving Fatalities: A Comprehensive Approach to a Persistent Problem (Teutsch et al., 2018).