Blood alcohol concentration (BAC) laws set legal limits for drivers’ blood alcohol concentration. In the United States, lower BAC limits are set for drivers under the legal drinking age. In other countries, lower levels often apply to newly licensed drivers or newly licensed drivers under a specified age (CG-Motor vehicle injury). High BAC levels have a detrimental effect on drivers’ physical and cognitive abilities, including muscle coordination, speed control, and perception (NHTSA-Drunk driving).
Expected Beneficial Outcomes (Rated)
Reduced alcohol-related crashes
Reduced fatal and non-fatal injuries
Evidence of Effectiveness
There is strong evidence that 0.08% blood alcohol concentration (BAC) laws reduce alcohol-related motor vehicle crashes and fatalities compared to higher BAC levels (CG-Motor vehicle injury, NICE-Killoran 2010, Bernat 2004*). Setting lower BAC limits for young or inexperienced drivers has also been shown to reduce crashes and fatalities (CG-Motor vehicle injury, Fell 2016*, Romano 2015*).
Lowering BAC limits from 0.10% to 0.08% appears to be associated with increases in arrests due to driving under the influence (DUI) (Schwartz 2013*). Reducing BAC limits further (e.g., from 0.08% to 0.05%) can result in greater reductions in crashes and fatalities (NICE-Killoran 2010, Fell 2014*, Martin 2013*).
Impact on Disparities
As of January 2016, all 50 states and Washington DC have blood alcohol concentration (BAC) limits of 0.08% for drivers age 21 and over (APIS). Utah’s amendment to the BAC bill, scheduled to take effect on December 30th, 2018, reduces the limit to 0.05% in the state (UT BAC laws).
Zero tolerance laws make it illegal for individuals under the age of 21 to drive with any measurable amount of alcohol in their systems; 14 states and Washington DC have BAC limits of 0.00% for drivers under 21 and 34 states have limits of 0.02% (APIS).
Citations - Evidence
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CG-Motor vehicle injury - The Guide to Community Preventive Services (The Community Guide). Motor vehicle injury prevention.
NICE-Killoran 2010 - Killoran A, Canning U, Doyle N, Sheppard L. Review of effectiveness of laws limiting blood alcohol concentration levels to reduce alcohol-related road injuries and deaths: Final report. London, UK: National Institute for Health and Care Excellence (NICE); 2010.
Bernat 2004* - Bernat DH, Dunsmuir WTM, Wagenaar AC. Effects of lowering the legal BAC to 0.08 on single-vehicle-nighttime fatal crashes in 19 jurisdictions. Accident Analysis & Prevention. 2004;36(6):1089-97.
Fell 2016* - Fell JC, Scherer M, Thomas S, Voas RB. Assessing the impact of twenty underage drinking laws. Journal of Studies on Alcohol and Drugs. 2016;77(2):249-260.
Romano 2015* - Romano E, Scherer M, Fell J, Taylor E. A comprehensive examination of US laws enacted to reduce alcohol-related crashes among underage drivers. Journal of Safety Research. 2015;55:213-221.
Schwartz 2013* - Schwartz J, Davaran A. Enforcement following 0.08% BAC law change: Sex-specific consequences of changing arrest practices? Addictive Behaviors. 2013;38(10):2506-2512.
Fell 2014* - Fell JC, Voas RB. The effectiveness of a 0.05 blood alcohol concentration (BAC) limit for driving in the United States. Addiction. 2014;109(6):869-874.
Martin 2013* - Martin TL, Solbeck PAM, Mayers DJ, et al. A review of alcohol-impaired driving: The role of blood alcohol concentration and complexity of the driving task. Journal of Forensic Sciences. 2013;58(5):1238-1250.
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