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, limited primarily to property damage-only accidents. We believe these results may be partially explained by drivers who, after the policy is enacted, avoid reporting property damage-only accidents if possible. Using insurance claims data, we show there is no corresponding fall in insurance claims or payouts suggesting that the fall in total accidents likely comes from under-reporting