Business recession, alcohol consumption, drinking and driving laws: impact on Oklahoma motor vehicle fatalities and fatal crashes.

In 1982, Oklahoma enacted a series of drinking and driving laws. In the ensuing years, motor vehicle fatalities and fatal crashes were reduced by one-third. Factors contributing to this reduction were examined using interrupted time series analysis of monthly rates of motor vehicle deaths and fatal crashes for the period January 1980 to December 1986. Decreasing per capita alcohol consumption and increased unemployment apparently account for most of the fatality and fatal crash reduction in Oklahoma. The enactment of two traffic safety laws--one specifying the illegal blood alcohol concentration level (BAC law) and the other facilitating license withdrawal from suspected drunk drivers (administrative per se law)--together reduced Oklahoma traffic deaths and fatal crashes by about 9 percent. The effectiveness of the laws appeared to be greatest in the first two years following their enactment.