The effects of a jail diversion program on incarceration: a retrospective cohort study

J Am Acad Psychiatry Law. 1999;27(3):377-86.


The objective of this retrospective cohort study was to determine whether a jail diversion program significantly reduced the number of days of incarceration over the year following arrest in a sample of seriously mentally ill (SMI) people who had been arrested for a minor crime.

Methods: A group of 314 SMI detainees were diverted out of jail and into mental health treatment. They were compared with a sample of 124 people who would have been eligible for diversion but were not diverted. For each group, the authors compared the total days incarcerated in the year after index arrest. Analyses indicated that jail diversion significantly reduced incarceration time during the next year (40.51 versus 172.84 days, p = .0001). However, the effect of diversion differed depending upon the level of criminal charge: diversion significantly reduced jail time only among those who were arrested for more serious offenses. Those arrested for Class D felony and Class A misdemeanor charges and diverted into mental health treatment spent significantly less time in jail in the next year than those not diverted (260 and 110 fewer days, respectively; p = .0001 for both). Those arrested for Class B or C misdemeanors had similar days incarcerated regardless of diversion. These results remained after adjusting for age, race, gender, and diagnosis. This study presents the first evidence that jail diversion may produce positive longitudinal criminal justice outcomes for SMI people. It also suggests that diversion may not reduce incarceration in all sub-groups of SMI people who are arrested for minor crimes.

MeSH terms

  • Adult
  • Cohort Studies
  • Crime / psychology*
  • Female
  • Humans
  • Male
  • Mental Disorders / rehabilitation*
  • Mental Health Services*
  • Multivariate Analysis
  • New England
  • Prisoners / psychology*
  • Program Evaluation
  • Public Policy
  • Regression Analysis
  • Retrospective Studies
  • Risk
  • Time Factors