This paper presents an assessment of the external cost of drunk driving in Spain between 2004-2015. Eventually we arrive at the following conclusions. Firstly, we find the relative risk of drunk drivers causing a crash during the night (20:00 p.m. to 5:00 a.m.) to be between 2.7 to 3.9 times higher than that of sober drivers. Secondly, we provide evidence that the relative number of drunk drivers versus sober drivers declined during nighttime hours after the implementation of the Penalty Points System for driving licenses in Spain on July 1 st 2006. Thirdly, using logistic and count model regressions, we confirm hourly heterogeneity in the pattern of drunk driving, and estimate elasticities of fatal crashes with respect to drunk driving, which range between 0.5 and 0.7. When estimating the decline in fatalities after the Penalty Points System, our approach does a good job in capturing the change in fatalities during nighttime hours that can be accounted for by drunk driving. Finally, our assessment indicates a downturn in the external costs of drunk driving over the last decade in Spain. In addition, we estimate that the fine for drunk driving should be set at 1250€, in order to offset its external costs. Overall, our results point to a decline in drunk driving offences alongside an increase in its punition.