ing of neurobiological and behavioral aspects of drug use and has stimulated the development and testing of new modalities of treatment and their introduction into clinical practice (Institute of Medicine, 1996, 1998). Other funding streams in SAMHSA and other federal agencies have been developed for evaluating prevention and treatment programs. In recent years, new collaborative research efforts relating to offender populations have been undertaken by the National Institute of Justice and the Office of Juvenile Justice and Delinquency Prevention and the National Institute on Drug Abuse and the Substance Abuse and Mental Health Service Administration. Although, as this report details, the existing data systems need to be strengthened, and knowledge regarding the effectiveness of treatment and prevention activities still has significant gaps, an impressive body of research has emerged in these areas over the past several decades.

The nation has failed to make an equivalent investment in data and research on the effects of enforcement. Federal and state drug enforcement expenditures amounted to $19.5 billion in 1991 (the last year for which aggregate figures including state and local enforcement are available). Expenditures for federal enforcement (including interdiction and international enforcement) increased more than tenfold between 1981 and 1999. In 1998, 1.6 million people were arrested for drug offenses, three times as many as in 1980, and 289,000 new drug offenders were incarcerated in state prisons, more than ten times as many as in 1980 (23,900). The benefits and costs of these policies have been the subject of heated and continuing debate for decades. Yet policy makers are in no better position to evaluate the effectiveness of these activities than they were in 1973, when the National Commission on Marihuana and Drug Abuse and the first National Drug Control Strategy called attention to the “startling” gaps in knowledge about the effects of enforcement.

A small number of economists and policy analysts, supported by ONDCP and other agencies, have doggedly attempted to fill the void by developing analytic models and theories of illegal markets and by making efforts to predict the effects of different types of enforcement interventions. These efforts have helped to characterize the complex interactions of producers, dealers, and users and the subtle processes through which enforcement and other drug control policies might affect prices and consumption. However, as the committee noted in its Phase I report (National Research Council, 1999), even the most creative and sophisticated analytic model cannot inform policy making in the absence of sound data. The weaker the data, the less confidence one can have in the inferences