Drink...then Drive Away : The Effects of Lowering the BAC in Utah

In March of 2017 Utah became the first state in the United States to lower the legal blood alcohol content (BAC) for driving from 0.08 to 0.05 g/dL. We take advantage of the fact that enforcement was delayed until 2019 to test whether this policy change significantly affected the number of traffic accidents or the severity of those accidents. We employ a difference-in-differences strategy on Utah counties using neighboring states as controls. Results show the policy appears to decrease the total number of accidents in urban counties, limited primarily to property damage only accidents. Surprisingly, the strongest effects are found during weekday days. We confirm our findings using a synthetic control and a doubly robust difference-in-differences estimator. We believe these results may be partially explained by drivers who, after the policy is enacted, avoid reporting property damage only accidents if possible