Jail diversion programs for justice-involved individuals with mental illness or substance use disorders: a scoping review

To synthesize the conceptual foundations, program variations, documented outcomes, and future growth opportunities of jail diversion initiatives for individuals with serious mental illness or substance use disorders. A scoping review was conducted following established scoping review methodology. PubMed and PsycINFO were searched using the terms “jail diversion” and “mental health,” with filters for adult populations and English language. Following abstract screening, 36 unique sources were included after removal of 9 duplicates. Supplementary contextual sources identified through targeted searches were consulted for background information only and were not included in the formal evidence synthesis. Diversion programs typically use early screening, structured risk assessment, integrated treatment, ongoing supervision, and cross-agency collaboration. The 36 included studies document associations between jail diversion and lower reoffending, reduced psychiatric emergency service utilization, and cost savings across diverse settings. Program effectiveness was supported across multiple diversion types including police-led deflection, mental health courts, drug treatment courts, and prosecutor-coordinated post-booking programs. Study designs and effect sizes were heterogeneous. Jail diversion programs represent a promising, humane alternative to incarceration, with evidence across multiple settings suggesting reductions in recidivism and public expenditures alongside improvements in health and social stability. To realize their full promise, future efforts should secure sustainable financing, embed psychiatric care within diversion teams, adopt standardized success metrics, and strengthen post-program reentry supports.