"Courts allow participants to enter the program at a variety of points in the criminal justice process (see Table 2-3.1). Most courts reported multiple ways people could get into their drug court. The greatest percent of courts reported the point of entry for participants is 'after a plea is entered, but final disposition is suspended during treatment,' while the least frequent points of entry include 'as a part of parole violation' and 'as a community reentry from jail/prison program.'
"To understand the variety of paths into drug court that exist, we grouped courts into mutually exclusive categories of points of entry based on their answers to the measures in Table 2-3.1. For some courts, there was only one point in the process for entry; while for others, there were combinations of entry points. The most frequent court type for points of entry was the single selection of 'after a pleas is entered, but final disposition is suspended during treatment,' with 17.5 percent of courts selecting only this response. The next most frequent type of court in terms of points of entry was the combination of 'after case disposition' and 'as a part of probation violation,' with 11.1 percent of courts indicating these two responses. The frequencies of the remaining possible combinations of entry points ranged anywhere from 0.3 to 8.2 percent, indicating a wide variety of drug court entry structures among the courts.
"Despite the various entry points for participants allowed by courts, we examined at which point the majority of participants enter a single program. Consistent with the findings above, the largest portion of drug courts (44.7 percent) reported that the majority of participants enter the program 'after a plea is entered, before final disposition' (see Table 2-3.2). In very few cases are the majority of drug court participants probation violators (9.9 percent), parole violators (0.3 percent), or entering as part of a community reentry program (0.6 percent)."

Source

Rossman, Shelli B., et al., "Final Report, Volume 2: The Multi-Site Adult Drug Court Evaluation: What's Happening with Drug Courts? A Portrait of Adult Drug Courts 2004" (Washington, DC: Urban Institute, June 2011), pp. 37-38.
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