The Public Safety Impact of Shortening Lengthy Prison Terms

By Avinash Bhati

In Spring 2022, the Council on Criminal Justice (CCJ) launched the Task Force on Long Sentences. The group of 16 experts represents a broad range of experience and perspectives, including crime victims and survivors, formerly incarcerated people, prosecutors, defense attorneys, law enforcement, courts, and corrections. Its mission is to examine how long prison sentences—defined as 10 years or more—affect public safety, crime victims and survivors, incarcerated individuals and their families, communities, and correctional staff, and to develop recommendations to strengthen public safety and advance justice. The analysis presented here was commissioned by the Task Force to examine the relationship between long prison sentences and public safety in one state, Illinois. The project was made possible by a partnership between the Illinois Sentencing Policy Advisory Council, CCJ, and Maxarth LLC, a data analytics firm. Long sentences are often imposed with an expectation that they will prevent some crime by incapacitating individuals and deterring them from engaging in future crime after release. While there are several other purposes of sentencing, including punishing offenders, restoring victims and survivors, and deterring others from committing crimes, the research question explored in this brief is whether people serving long sentences may be confined beyond their likelihood of engaging in criminal behavior. Incarcerating individuals beyond this point would increase the size of the total prison population—and associated costs— without producing additional benefits for public safety. To examine this question, Maxarth LLC analyzed detailed arrest history data for people who were released from Illinois prisons between June 2016 and June 2019. For the 1,127 people in this release cohort who had served 10 years of more prior to release, microsimulations were created to estimate the number of arrests averted due to the individuals’ long prison terms.1 The number of arrests averted includes: (a) estimated arrests that did not happen because the person was incarcerated (incapacitation effect), (b) arrests that did not happen during a 30-month post-release tracking period because the person reduced their criminal activity (specific deterrence or rehabilitation effects), and (c) arrests that happened postrelease because the person increased their criminal behavior following their incarceration (criminogenic effect). The incapacitation effect was calculated using the length of each person’s prison stay (time served); the specific deterrence and criminogenic effects were calculated in the 30 months following each person’s release date. The analysis accounted for the start of the COVID-19 pandemic in March 2020, which overlapped with the 30-month post-release tracking period for some members of the sample. See the supplemental methodology report for detailed procedures.

Washington, DC: Council on Criminal Justice, 2023. 30p.