Blood Alcohol Concentration Laws (Per se Laws)
Per se laws— a specific BAC level (usually .05 or .08) at which a driver is considered legally impaired and can be arrested (Andenaes, 1988). The BAC can be measured by taking a blood sample from a driver or via an analysis of the exhaled breath. The invention of the breathalyser and other portable devices for collecting samples of drivers’ breaths, combined with per se legislation, revolutionized law enforcement of drinking and driving.
All USA states have longstanding laws prohibiting driving while impaired by alcohol. The U.S. Congress included a provision in the Fiscal Year 2001 Department of Transportation and Related Agencies Appropriations Act 213 requiring states and territories to implement .08 BAC laws by October 1, 2003 or risk losing federal highway construction funds. Certain policies depend upon laws that clearly define drinking and driving with a BAC at or higher than a prescribed level for the whole population (e.g., .08 or .05) or for young drivers (usually zero or .02).