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Lower (<.08) Blood Alcohol Concentration Limits

Description of Strategy

Currently all fifty states and the District of Columbia have per se laws stating that it is a crime to drive with a blood alcohol concentration (BAC) of .08 percent or higher. A per se impaired driving law indicates that drivers with a BAC of .08 percent or higher are intoxicated in the eyes of the law and no additional proof of impairment is necessary to obtain a conviction. Other countries, Australia for example, have implemented lower (.05 percent) BAC limits for adult drivers. In the United States, lower BAC laws only apply to drivers under the age of 21. The illegal BAC level for drivers under the age of 21 ranges from any detectable BAC to .02 percent. (Guide to Community Preventive Services, 2000).

In Wyoming, the legal BAC for drivers over 21 is <.08 percent. There is a zero tolerance law (BAC less than .02 percent) for drivers under the age of 21 (State of Wyoming Legislature, 2017).

Also known as...

Zero tolerance laws for drivers under age 21

Discussion of Effectiveness


Evidence provides strong support for the effectiveness of lower blood alcohol concentration limits for reducing the rate of drunk driving and alcohol-related crashes, fatalities, and injuries (Fell & Voas, 2006). Five studies in a 2006 review by Fell & Voas found that lowering the BAC limit to .05 percent reduced the percentage of drives with a BAC greater than .05 percent at roadside stops, decreased alcohol-related traffic crashes and fatalities, and reduced single nighttime vehicle crashes. A University of Wisconsin Population Health Institute systematic review (2017) reported similar findings. Reducing BAC limits to .05 was associated with reductions in motor vehicle crashes and fatalities. Evidence also supports lowering the BAC limit for youth and inexperienced drivers to .02 percent or lower for reducing driving after drinking and alcohol-related crashes (University of Wisconsin Population Health Institute, 2017; Guide to Community Preventive Services, 2000).