This is the final report of a project entitled "State of Knowledge of Drug-Impaired Driving." The project was conducted by Mid-America Research Institute, Inc., of New England for the National Highway Traffic Safety Administration (NHTSA). David Shinar of Ben Gurion University of the Negev, Israel, and J. Michael Walsh of The Walsh Group, Bethesda, Maryland, made significant contributions, Professor Shinar writing much of the material in Chapter 4, and Dr. Walsh writing the bulk of Chapter 3. Dr. Walsh also reviewed the provisions of state laws on drugged driving contained in Chapter 6. This review of drug-impaired driving examines research published during the 1981-2001 period, and references some of the earlier material contained in prior reviews.

The first comprehensive review of the state of knowledge about drugs other than alcohol and highway safety in this country was the landmark report by Joscelyn and Maickel (1975). That review was updated in a report by Joscelyn, Donelson, Jones, et al. (1980) which provided input to NHTSA's 1979 report to Congress on drugs and driving (National Highway Traffic Safety Administration , 1979). About this same time, NHTSA had sponsored the study Drug Research Methodology which laid some of the groundwork for future research in this field (Donelson, Marks, Jones et al., 1980). The last update review of the state of knowledge about drugs and highway safety was conducted by Compton (1988) and was also documented in a report to Congress. In the meantime, there has been some significant research in the field, some of which has been sponsored by NHTSA, but much of which has been conducted outside the United States. This update review examines the validity and utility of research published since December 31, 1980 for developing public policy, including policy relating to the development of new research and development initiatives.

The remainder of the body of this report is presented in six chapters. Chapter 2 following this introduction contains a description of the methods we followed in determining the topics and issues of concern in the update; identifying, acquiring and screening the documents to be reviewed; and conducting the individual reviews. Chapter 3 is concerned with research pertinent to the detection and measurement of drugs in drivers, and Chapter 4 reviews the experimental literature, including research conducted in a laboratory testing human performance on tasks believed to be related to driving, and research conducted either in a driving simulator or on a closed course testing performance in actual driving tasks. In Chapter 5, we examine literature flowing from epidemiologic studies of drugs and traffic crashes, including literature on the drug use of various subgroups of drivers such as drivers arrested for drunk driving or "drugged" driving. Chapter 6 deals with literature on countermeasures for drug-impaired driving, and Chapter 7 presents our conclusions and recommendations. An index of terms and a bibliographic listing of references follow.

The authors gratefully acknowledge the contribution to this review of Professor Roger P. Maickel of Purdue University, and Dr. Jon Eric Sprague, a post-doctoral student of Professor Maickel, for their help in preparing assessments of the literature for an earlier draft of this review. We are also appreciative of the assistance of our colleagues in the field of alcohol, drugs, and traffic safety for their help in identifying pertinent literature.