Alcohol, Drugs, and Impaired Driving addresses many theoretical and practical issues related to the role played by alcohol and other psychoactive drugs on driving performance, road-traffic safety, and public health. Several key forensic issues are involved in the enforcement of laws regulating driving under the influence of alcohol and/or other drugs, including analytical toxicology, pharmacology of drug action, as well as the relationships between the dose taken, the concentration levels in body fluids, and the impairment of performance and behavior. Our knowledge about drunken driving is much more comprehensive than drugged driving, so a larger part of this book is devoted to alcohol-induced impairment, rather than driver impairment caused by other psychoactive substances. For convenience, the book is divided into four main sections. The first section gives some historical background about the analysis of ethanol in blood and breath in forensic science and legal medicine. The important role of the Breathalyzer instrument in traffic-law enforcement, especially in Australia, Canada, and the USA is presented along with a biographical sketch of its inventor (Professor Robert F. Borkenstein of Indiana University) with focus on the man, his work, and his impact. The second section discusses several issues related to forensic blood- and breath-alcohol analysis as evidence for the prosecution of traffic offenders. This includes how the results should be interpreted in relation to the impairment effects and an evaluation of common defense challenges. Because most countries have adopted concentration per se laws, the main thrust of the prosecution case is the suspect's measured blood- or breath-alcohol concentration. This legal framework necessitates that the analytical methods used are "fit for purpose" and are subjected to rigorous quality assurance procedures. The third section gives a broad overview of the current state of knowledge about driving under the influence of non-alcohol drugs in various countries. This includes adoption of zero-tolerance laws, concentration per se statutes, and clinical evidence of driver impairment based on field sobriety tests and drug recognition expert evidence. The fourth section deals with epidemiology, enforcement, and countermeasures aimed at reducing the threat of drunken and drugged driving. All chapters have been previously published in the international journal Forensic Science Review, although they are now updated with recent developments, current data, and the latest literature references. The book provides a convenient collection of peer-reviewed articles covering a broad overview of alcohol/drugs and impaired driving, including toxicological analysis, and considerations for interpretation of the results in connection with enforcement of drunk- and drugged-driving laws in various countries.