Unraveling decarceration policy and how it affects correctional populations

Abstract

Following decades of mass incarceration, states have enacted policies to reverse prison growth, producing population declines for the first time in four decades. Decarceration, the intentional reduction of prison populations, has gained momentum, often through strategies that divert lower-risk individuals from incarceration. However, the effects of these reforms are complex and sometimes unsustainable. As decarceration expands, policymakers need clearer evidence on how reforms affect correctional populations. This study examines Washington State from January 1, 2015, through December 31, 2025. Using administrative data from 116,559 cases, we employ interrupted time-series analysis to assess four policy changes and their effects on readmissions, first-time prison admissions, and technical violations. Results suggest that population decline was not the product of a single reform, but reflected the cumulative response of a correctional system adapting to overlapping policy changes and institutional pressures. By focusing on system flow, this study clarifies how decarceration unfolds inside correctional systems.

John Ursino

Research Specialist

My research focuses on advancing evidence-based practices in criminal justice. Primary areas of research include evaluating and constructing risk-need assessments to enhance decision-making processes, addressing challenges related to prison and jail crowding, and exploring correctional system reforms.

Zachary Hamilton

Professor

My research centers on innovation in risk and needs assessment development.