In a 2003 report, New York's Center for Court Innovation compared recidivism rates between drug court graduates and attendees from six different drug courts, and control groups of similar defendants not entering drug court. They found that "Graduation is itself a powerful predictor of avoiding postprogram recidivism; those who failed drug court were far more likely to recidivate in the post-program period. Further, contrary to previous research with non-drug court populations, no benefit was found to spending more total time in treatment only to fail in the end. Among those who failed, more time in the drug court program (measured in four courts) or more days specifically attending treatment (measured in one court) had no impact on post-program recidivism. These results strongly point to drug court graduation as the pivotal indicator of long-term outcomes."

Source

Rempel, Michael, Dana Fox-Kralstein, Amanda Cissner, Robyn Cohen, Melissa Labriola, Donald Farole, Ann Bader and Michael Magnani, "The New York State Adult Drug Court Evaluation: Policies, Participants and Impacts" (New York, NY: Center for Court Innovation, Oct. 2003), p. xiii.
http://www.courtinnovation.or…