The Relationship Between Sentence Length, Time Served, and State Prison Population Levels

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 sentences of 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 sentence length and actual time served in prison.

Previous research for the Task Force shows that in recent years the share of the total U.S. prison population with sentences of 10 or more years has increased, driven by fewer people serving shorter terms. In 2019, 56% of people in prison were serving a long sentence, up from 46% in 2005. Over the same period, there was a 60% increase in the average amount of time served by people who were released after serving a long sentence.

This work builds on research conducted as part of the Robina Institute of Criminal Law and Criminal Justice’s Prison Release: Degrees of Indeterminacy (DOI) project, which examined the statutory and administrative policy frameworks that govern prison release (and thus time served) in each state, evaluated how these policies produced sizeable changes to time served in Colorado, and explored how back-end release discretion affects prison population levels across the United States. This brief summarizes the relevant findings from the DOI project and provides additional analysis of the relationship between sentence length and time served.