Two of these studies indicate that .08 BAC laws have reduce alcohol-related crash involvement, particularly in conjunction with the presence of other impaired driving laws and programs such as administrative license revocation (ALR). The third study looked at the effect of a .08 BAC law in a single state (NC) and found no statistically significant change in a pre-existing downward trend in factors related to alcohol-related crashes.
The most comprehensive study (covering all 50 states) analyzed the effects of both .08 and .10 illegal per se laws, as well as administrative license revocation (ALR) laws over a 16-year time period. After extensive efforts to control for extraneous factors, this study found that all three laws were associated with reductions in driver involvement in alcohol-related fatal crashes.
It estimated that .08 BAC laws had an 8% effect in reducing fatal crashes involving drivers at both high BACs and lower BACs and resulted in 275 fewer fatalities in the 16 states where they were in effect in 1997. If all 50 states had such laws in effect, an additional 590 fatalities would have been prevented. All three laws were associated with reduced alcohol (beer) consumption levels.
An 11-state study also examined the effects of .08 BAC (and ALR) laws. It found that 0.08 BAC legislation was associated with reductions in alcohol-related fatalities, alone or in conjunction with ALR laws, in seven of the eleven states studied. In five of these states (VT, KS, NC, FL, NM), implementation of the 0.08 BAC law itself was associated with significantly lower rates of alcohol related fatalities.
These results take into account any pre-existing downward trends the states were already experiencing, due to other factors such as the presence of other laws, use of sobriety checkpoints, etc. In two states (CA and VA), significant reductions were associated with the combination of .08 BAC and ALR laws, implemented within 6 months of each other. This study also found evidence of reduced alcohol (beer) consumption in several states following implementation of .08 laws.
The third study studied the effects of a .08 BAC law implemented in 1993 in North Carolina, a state which had already been experiencing a sharp decline in alcohol-related fatalities since 1987. This study concluded that there was little clear effect of the lower BAC limit. Results from various analyses suggested that some portion of the reductions may have been associated with the law but the magnitude of these effects was not sufficient to make this conclusion.
In aggregate, these three studies provide additional support for the premise that .08 BAC laws help to reduce alcohol-related fatalities, particularly when they are implemented in conjunction with other impaired driving laws and programs.
Nearly all of the findings of these and previous studies show changes that suggest that .08 BAC legislation (as well as .10 BAC laws and ALR laws) have contributed to the trend toward reduced alcohol-related crashes and fatalities that have been experienced across the nation.
