In 2001, the European Commission adopted Recommendation (2001/115/EC) on the maximum blood alcohol concentration (BAC). Today, most Member States have adopted legislation fixing maximum BAC limits in accordance with it. The measures aimed at tackling the problem of driving under the influence of alcohol or other psychoactive substances belong to the domain of driver behaviour, which remains in the remit of Member States competences. Nevertheless, almost twenty years after the recommendation was adopted, driving under the influence of alcohol remains one of the most common accident factors. In the Strategic Action Plan on Road Safety adopted as part of the III Mobility Package (Annex I to COM(2018) 293 final), the Commission committed to evaluate how to strengthen the Commission recommendation of 2001. This study is intended to provide the Commission services with up-to-date information on the role of alcohol and other psychoactive substances as accident causation factors and policies and measures implemented by Member States to address driving under the influence of alcohol and drugs. Specifically, the study provides information on: Prevalence and impacts of driving under the influence of alcohol and drugs; Legal frameworks, enforcements and sanctions currently in place; Technologies for enforcement of driving under the influence of alcohol and drugs; Technologies for prevention of driving under the influence of alcohol and drugs, including a cost-benefit analysis of the installation of alcohol interlock devices.