Of the 1,700 drug court programs operating or planned as of September 2004, about 1,040—nearly 770 operating and about 270 being planned— were adult drug court programs, according to data collected by the Office of Justice Programs’ Drug Court Clearinghouse and Technical Assistance Project. The primary purpose of these programs is to use a court’s authority to reduce crime by changing defendants’ substance abuse behavior. In exchange for the possibility of dismissed charges or reduced sentences, eligible defendants who agree to participate are diverted to drug court programs in various ways and at various stages in the judicial process. These programs are typically offered to defendants as an alternative to probation or short-term incarceration. Drug court programs share several general characteristics but vary in their specific policies and procedures because of, among other things, differences in local jurisdictions and criminal justice system practices. In general, judges preside over drug court proceedings, which are called status hearings; monitor defendants’ progress with mandatory drug testing; and prescribe sanctions and rewards as appropriate in collaboration with prosecutors, defense attorneys, treatment providers, and others. Drug court programs also vary in terms of the substance abuse treatment required. However, most programs offer a range of treatment options and generally require a minimum of about 1 year of participation before a defendant completes the program. In order to determine defendants’ eligibility for participation, drug court programs typically screen defendants based on their legal status and substance use. The screening process and eligibility criteria can vary across drug court programs. According to the literature, eligible drug court program participants ranged from nonviolent offenders charged with drug-related offenses who have substance addictions to relatively medium- risk defendants with fairly extensive criminal histories and failed prior substance abuse treatment experiences. Participants were also described as predominantly male with poor employment and educational achievements. Appendix IV presents additional information about the general characteristics of drug court programs and participants in the evaluations we reviewed. Research on drug court programs has generally focused on program descriptions and process measures, such as program completion rates, and presented limited empirical evidence about the effectiveness of drug court programs in reducing recidivism and substance use. In 1997, we reported on 12 evaluations that met minimum research standards and concluded that the evaluations showed some positive results but did not firmly establish whether drug court programs were successful in reducing offender recidivism and substance use relapse. More recently, two syntheses of multiple drug court program evaluations have drawn positive conclusions about the impact of drug court programs. One synthesis concluded that criminal activity and substance use are reduced relative to other comparable offenders while participants are engaged in the drug court program, and that program completion rates ranged from 36 to 60 percent. Further, the other synthesis reported that drug offenders participating in a drug court program are less likely to re-offend than similar offenders sentenced to traditional correctional options, such as probation. Some of the evaluations included in these two syntheses had methodological limitations such as, the lack of strong comparison groups and the lack of appropriate statistical controls. Some did not use designs that compared all drug court program participants—including graduates, those still active, and dropouts—with similar nonparticipants. For example, they compared the outcomes of participants who completed the program with the outcomes of those who did not (that is, dropouts). These evaluations, upon finding that program graduates had better outcomes than dropouts, have concluded that drug court programs are effective. This is a likely overestimation of the positive effects of the intervention because the evaluation is comparing successes to failures, rather than all participants to nonparticipants. Additionally, other evaluations did not use appropriate statistical methods to adjust for preexisting differences between the program and comparison groups. Without these adjustments, variations in measured outcomes for each group may be a function of the preexisting differences between the groups, rather than the drug court program. In most of the evaluations we reviewed, adult drug court programs led to recidivism reductions during periods of time that generally corresponded to the length of the drug court program—that is, within-program. Our analysis of evaluations reporting recidivism data for 23 programs showed that lower percentages of drug court program participants than comparison group members were rearrested or reconvicted. Program participants also had fewer incidents of rearrests or reconvictions and a longer time until rearrest or reconviction than comparison group members. These recidivism reductions were observed for any felony offense and for drug offenses, whether they were felonies or misdemeanors. However, we were unable to find conclusive evidence that specific drug court program components, such as the behavior of the judge, the amount of treatment received, the level of supervision provided, and the sanctions for not complying with program requirements, affect participants’ within-program recidivism. Post-program recidivism reductions were measured for up to 1 year after participants completed the drug court program in several evaluations, and in these the evidence suggests that the recidivism differences observed during the program endured. A more detailed description of the recidivism reduction results is included in appendix V. Evidence about the effectiveness of drug court programs in reducing participants’ substance use relapse is limited and mixed. The evidence included in our review on substance use relapse outcomes is limited to data available from eight drug court programs. The data include drug test results and self-reported drug use; both measures were reported for some programs. Drug test results generally showed significant reductions in use during participation in the program, while self-reported results generally showed no significant reductions in use. Appendix VI presents additional information about the evaluations we reviewed that reported on substance use relapse outcomes. Completion rates, which refer to the number of individuals who successfully completed a drug court program as a percentage of the total number admitted, in the programs we reviewed that assessed completion ranged from 27 to 66 percent. As might be expected, program completion was associated with participants’ compliance with program requirements. Specifically, evaluations of 16 adult drug court programs that assessed completion found that participants’ compliance with procedures was consistently associated with completion. These program procedures include attending treatment sessions, engaging in treatment early in the program, and appearing at status hearings. No other program factor, such as the severity of the sanction that would be invoked if participants failed to complete the program and the manner in which judges conducted status hearings, predicted participants’ program completion. Several characteristics of the drug court program participants themselves were also associated with an increased likelihood of program completion. These characteristics include lower levels of prior involvement in the criminal justice system and age, as older participants were more likely to complete drug court programs than younger ones. Appendix VII presents additional information about the evaluations we reviewed that reported on program completion. A limited number of evaluations in our review discussed the costs and benefits of adult drug court programs. Four evaluations of seven drug court programs provided sufficient cost and benefit data to estimate their net benefits (that is, the benefits minus costs). The cost per drug court program participant was greater than the cost per comparison group member in six of these drug court programs. However, all seven programs yielded positive net benefits, primarily from reductions in recidivism affecting both judicial system costs and avoided costs to potential victims. Net benefits ranged from about $1,000 per participant to about $15,000 in the seven programs. These benefits may underestimate drug court programs’ true benefits because the evaluations did not include indirect benefits (such as reduced medical costs of treated participants). Financial cost savings for the criminal justice system (taking into account recidivism reductions) were found in two of the seven programs. We provide additional information about the reported costs and benefits of drug court programs we reviewed in appendix VIII. Overall, positive findings from relatively rigorous evaluations in relation to recidivism, coupled with positive net benefit results, albeit from fewer studies, indicate that drug court programs can be an effective means to deal with some offenders. These programs appear to provide an opportunity for some individuals to take advantage of a structured program to help them reduce their criminal involvement and their substance abuse problems, as well as potentially provide a benefit to society in general. Although not representative of all drug court programs, our review of 27 relatively rigorous evaluations provides evidence that drug court programs can reduce recidivism compared to criminal justice alternatives, such as probation. These results are consistent with those of past reviews of drug court evaluations. Positive results concerning recidivism are closely associated with program completion. Specifically, while drug court participation is generally associated with lower recidivism, the recidivism of program completers is lower than for participants in comparison or control groups. Thus, practices that encourage program completion may enhance the success of drug court programs in relation to recidivism. While our review sheds little light on the specific aspects of these programs that are linked to positive recidivism outcomes, both participant compliance with drug court procedures and some participant characteristics seem to be related to success. To the extent that research can help to discern best practices for drug courts, the models for effective programs can be enhanced. Specifically, to the extent that drug court program managers can learn more about methods to retain participants for the duration of the program, they may be able to further enhance the positive impacts of drug court programs. We requested comments on a draft of this report from the Attorney General and the Director of ONDCP. Department of Justice officials informed us that the agency had no comments on the report. ONDCP officials informed us that the agency generally concurred with our findings. We are sending copies of this report to other interested congressional committees, the Attorney General, and the Director of the Office of National Drug Control Policy. We will also make copies available to others upon request. In addition, the report will be available at no charge on GAO’s Web site at http://www.gao.gov. If you or your staff have any questions concerning this report, please contact me at (202) 512-8777 or by e-mail at EkstrandL@gao.gov or William J. Sabol, Assistant Director, at (202) 512-3464, or SabolW@gao.gov. Key contributors to this report are listed in appendix IX.