Breath testing and highway fatality rates

Abstract

This paper presents an empirical investigation of the effect of a preliminary breath test law on highway fatality rates. A preliminary breath test law reduces the procedural problems associated with obtaining evidence of drunk driving and thus increases the probability that a drunk driver will be arrested. According to the theory of deterrence, increasing the probability of arrest for drunk driving will reduce the occurrence of this behaviour. The data set employed to test the theory is a time series from 1980 to 1985 of cross sections of the 48 contiguous states of the United States. Four highway fatality rates are used as measures of drunk driving. The effect of the breath test law was estimated using four independent variable models and 12 dummy variable models. The four independent variable models were also estimated using Learner's specification test. The purpose of using these alternative specifications and Learner's specification test was to examine the breath test coefficients for specification bias. The econometric results show that the passage of a breath test law has a significant deterrent effect on drunk driving. Simulations with these results suggest that if all states had a preliminary breath test law, highway fatalities could be reduced by about 2000 deaths per year