Abstract: This paper analyzes the effects of lowering the legal blood alcohol content limit for drivers from 0.05 to 0.03 grams of alcohol per deciliter of blood (g/dL) and increasing license suspension periods for offenders. We take advantage of a rich data set of administrative records that allow us to identify direct measures of accidents involving alcohol including fatalities and injuries. Results show a significant decrease of 32% in alcohol-related car accidents right after the law was approved but the effects moderate over time (15% after three years). There is also a significant reduction in injuries (31% right after the approval and 11% after three years) but no statistically significant effects on deaths. Complementary analysis of blood samples shows that the law had an effect on blood alcohol content (BAC) of male drivers up to the 90th percentile of the BAC distribution.