Enforcement of Zero Tolerance in the State of Washington - Evidence from Breath-Test Records.

Several studies have demonstrated the effectiveness of zero tolerance (ZT) laws that make it illegal for drivers younger than 21 years to have any measurable alcohol in their bodies when operating a vehicle. All 50 states in the United States now have such laws. However, there is some question as to the extent they are being enforced. Because it has a centralized file of all breath tests performed by police in that state, Washington provided a special opportunity to evaluate the extent of ZT enforcement. Analyses were performed on arrests and alcohol-related fatal crashes of drivers younger than 21 years using data from the Washington State Patrol Breath Test Section and from the National Highway Traffic Safety Administration Fatality Analysis Reporting System, respectively. The results indicate that low blood alcohol concentration citations increased and crashes were reduced for drivers younger than 21 years, but crashes for drivers older than 21 years also declined. This suggests that the decline in underage drinking drivers in fatal crashes could not be unequivocally attributed to the ZT law.