Evaluating the Effectiveness of a 0.08% BAC Limit and Other Policies Related to Drunk Driving

During the 1980s and 1990s in the United States, a large number of new policies have been adopted with the aim of reducing drunk driving. The value of many of these policies is controversial in policymaking circles. Recently the illegal per se blood alcohol content (BAC) limit, which is either 0.10% or 0.08% in nearly all states, has come under scrutiny from the federal government. This study presents new findings on the effectiveness of the 0.08 BAC limit, and drunk driving policies in general. The results indicate that the incremental effect of moving from a 0.10% BAC limit to a 0.08% standard lowers fatal traffic crash rates by 2.6%. This study analyzes the timing of the effects of the 0.08% limit, and finds that conventional empirical models do not capture an interesting pattern, in which the strongest effects of the law do not appear to set in until several years after enactment. Also, this paper sketches a welfare analysis of the change from a 0.10% limit to a 0.08% limit. In the context of the drunk driving policy literature in general, the paper evaluates two factors which have previously been ignored in this type of analysis: graduated licensing programs and the Mothers Against Drunk Driving (MADD) organization. Both initiatives are estimated to reduce fatal traffic crash rates. Graduated licensing, in fact, appears to be one of the most effective initiatives, reducing fatal crash rates for all drivers by 4.7%, and fatal crash rates for drivers under 21 by 11.5%. Other apparently significant policies are open container laws (5.1% reduction in fatal crash rates for all drivers), dram shop laws (5.8%), seat belt laws (4.9%), and beer taxes (0.8% per 10 cents). This paper also provides new evidence on "zero tolerance" BAC limits for drivers under 21, indicating that these laws reduce fatal crash rates for under 21 drivers by 6.1%, but only in the presence of administrative license revocation (ALR) laws.