Do tougher DUI sanctions reduce crashes and fatalities? Evidence from Brazil’s federal highways after the 2008 and 2021 reforms

This study investigates the effects of Brazilian zero tolerance alcohol policies, implemented in 2008 and revised in 2021, on accident and mortality levels along federal highways. The analysis uses a monthly panel from 2007 to 2023 and applies a difference in differences model to identify structural changes in driver behavior following the legal reforms. The empirical strategy is based on comparing weekdays, weekends and holidays, which represent different levels of exposure to the risk associated with driving under the influence of alcohol. The results show that the 2021 legislation produced stronger and more consistent effects, with significantly larger reductions in accidents and deaths compared with the 2008 version. The superior performance of the recent reform is associated with increased penalty severity, expanded conditions for criminal accountability and greater predictability of enforcement. From a theoretical perspective, the findings reflect a combination of rational deterrence and loss aversion, suggesting that raising the expected cost of the infraction modifies both perceived utility and the cognitive salience of risk. The results reinforce that road safety policies are more effective when they combine institutional robustness, continuous enforcement and mechanisms of normative internalization.