Driving under the influence of drugs: An overview of current legal frameworks

Driving under the influence (DUI) of alcohol and/or illicit drugs has been shown to increase the risk of involvement in road traffic collisions. Thanks to the scientifically proven link between blood alcohol concentration and impaired driving ability, a broadly accepted legislative framework has been established and is now widely adopted across the globe. In contrast, less is known about the effects of illicit drugs, and a clear correlation between blood drug concentrations and driving performance has been defined by some authors as a "mirage". In this review, we examine the advantages and limitations of current legislative initiatives regulating DUI of psychoactive drugs. The predominant approaches employed are "zero tolerance", "legal limits", and "impairment assessment". We discuss the distinctions among these methods, focusing on their implications for balancing citizens' rights and public safety. Additionally, we address the pre-analytical, analytical, and post-analytical challenges associated with the implementation of each legislative framework. The application of these three approaches is also discussed in light of recent changes in drug policies observed in many countries, including the decriminalization of certain substances, such as cannabis, and the growing prevalence of drugs prescribed for medical purposes. In conclusion, due to the absence of a robust scientific foundation, determining the most appropriate approach among the three remains challenging. The choice of method is primarily influenced by the government's policy priorities, which may emphasize either the protection of citizens' rights or the promotion of road safety.