Lowering the illegal BAC limit from 0.10 to 0.08 has resulted in 5-16% reductions in alcohol-related crashes, fatalities, or injuries in the United States, and saves about 400 lives each year (Fell and Voas, 2006; Shults et al., 2001; Tippetts et al., 2005; Kaplan and Prato, 2007; Wagenaar et al., 2007a).
A number of high-quality studies have evaluated the effects of lowering the legal BAC limit for driving on alcohol-related traffic crashes. Recently, Fell and Voas (2006) reviewed this literature, focusing particularly on 14 studies of the experiences in the United States. The clear majority of studies show reduction in alcohol-related traffic crashes associated with reduced BAC limits, with effects ranging from 5% to 16%. Shults et al. (2001) also included legally allowable BAC policies as part of their systematic review and found strong evidence for the effectiveness of these laws.
Two recently published high-quality studies present the most comprehensive evaluations of legally allowable BAC legislation. Tippets et al. (2005) evaluated the effects of lowering the legally allowable BAC from 0.10 to 0.08 g/dl in 19 jurisdictions in the United States. They found significant reductions in drinking-drivers in fatal crashes in 9 of the 19 jurisdictions, with an additional 7 jurisdictions showing reductions that were not statistically significant. Pooling across the 16 states where reductions were observed, they estimated a 15% average reduction in alcohol-related traffic crash fatalities following the change in the legally allowable BAC from 0.10 to 0.08 g/dl.
Wagenaar et al. (2007a) examined the effects of changes in the legally allowable BAC limit in 28 states from 1976 through 2002 on four measures of alcohol-related traffic crash involvement. They noted considerable variability of effects across states. However, pooled results across states confirmed that changes in legally allowable BAC limit significantly affect the overall burden of fatal crash mortality. They estimated that the move from 0.10 to 0.08 g/dl legal limits in the United States prevents 360 deaths each year. Further, an additional 535 deaths per year would be prevented if the legally allowable BAC limit were lowered from 0.08 to 0.05 g/dl, consistent with legal limits among most countries worldwide. These results were confirmed by Kaplan and Prato (2007). They found an 8% reduction in fatalities associated with lower BAC limits analyzing 22 states, using a different statistical approach than Wagenaar et al.