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Effectiveness: 4 Star Cost: $
Use: Low
Time: Short

All States have illegal per se BAC limits of .08 g/dL with the exception of Utah, which enacted a .05 g/dL law that went into effect at the end of 2018. All States also have BAC limits of .02 g/dL or lower for drivers under 21. These laws reinforce minimum drinking age laws prohibiting people under 21 from purchasing or possessing alcohol in public in all States. As of November 2016, Nebraska, North Carolina, Vermont, and Virginia set BAC limits of .02 or .04 g/dL for people convicted of DWI to emphasize they should not drive after drinking even moderate amounts (NCSL, 2016b).

Use: Four States have lowered BAC limits for people convicted of DWI (NCSL, 2016b).

Effectiveness: In 1988 Maine established a .05 g/dL BAC limit for 1 year after a first DWI offense and for 10 years after a subsequent offense. Violators received administrative license suspensions. In 1995 this BAC limit was lowered to .00 g/dL. Hingson et al. (1998) evaluated the 1988 law and concluded that it reduced the proportion of fatal crashes that involved repeat offender drivers by 25%. Jones and Rodriguez-Iglesias (2004) evaluated the overall effects of both laws, using data from 1988 to 2001. They also concluded that the laws contributed to a reduction in the proportion of repeat offenders in fatal crashes, primarily due to a reduction in drivers at BACs of .10 g/dL and higher.

Costs: Implementation and operation costs are minimal. Jones and Rodriguez-Iglesias (2004) found that Maine’s laws had little or no cost effect on the operations of the DWI control system.

Time to implement: Lower BAC limit laws can be implemented as soon as legislation is enacted.

Other issues:

  • Lower BAC limits for all drivers: Laboratory studies show impairment in driving ability begins at levels below .08 g/dL BAC. Consequently, many countries and some U.S. jurisdictions impose penalties for all drivers who have BACs of .05 g/dL or higher, not just repeat offenders (Colorado has a driving while ability impaired law and West Virginia may revoke your license at a BAC above .05g/dL). Evaluations from other countries suggest lower BAC limits reduce alcohol-impaired crashes (NHTSA, 2003b). For example, a law introduced in British Columbia, Canada, in 2010 included an administrative 3-day license suspension and possible vehicle impoundment for drivers with BACs from .05 to .08 g/dL. The law was intended to maximize deterrence by increasing the certainty and swiftness of sanctions. In the year after the law took effect, there was a 40% decrease in alcohol-related fatal crashes (Macdonald et al., 2013). Moreover, roadside surveys revealed a 44% decrease in drivers with BACs of .05 g/dL or higher, and a 59% decrease in drivers with BACs over .08 g/dL (Beirness & Beasley, 2014). In sum, administrative penalties beginning at .05 g/dL BAC appear to increase deterrence among the general population without creating additional burdens on the court system. A majority (63%) of drivers in the United States support lowering the BAC limit for all drivers from .08 to .05 g/dL (AAAFTS, 2014). The National Transportation Safety Board (NTSB) has recommended a BAC of .05 g/dL for all drivers (NTSB, 2013).