CCJ report explores "The Relationship Between Sentence Length, Time Served, and State Prison Population Levels"

I keep noting this post from last year discussing the Council of Criminal Justice's impressive Task Force on Long Sentences, in part because that Task Force is continuing to produce all sorts of important research and analysis concerning long sentences (see prior posts linked below).  The latest report, which is available here, is authored by Gerald Gaes and Julia Laskorunsky and is titled "The Relationship Between Sentence Length, Time Served, and State Prison Population Levels."  Here is the part of the report's introduction and "key takeaways": 

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, 57% 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 with long sentences.

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.

Key Takeaways

• Actual time served in prison is often quite different from the sentence length pronounced in court, and therefore sentence length alone only partially explains the individual and policy-level implications of long sentences.
• The relationship between sentence length and time served varies greatly across states and jurisdictions due to the difference in the legal and statutory framework that governs prison release.
• States that have higher than average sentence length also have higher than average time served, but the relationship between these two factors is modest.
• The average judicial maximum sentence in states with highly indeterminate systems (7 years) is twice as long as in highly determinate states (3.5 years). However, the difference in average time served in highly indeterminate and highly determinate states is much narrower, ranging between 2.1 and 2.6 years.
• Some states are much more likely to impose long prison sentences than others. The proportion of people entering prison with long sentences ranges from 2% in Colorado to 66% in Michigan.
• Individuals serving long sentences in states with highly determinate systems spend, on average, nearly three times as long in prison as individuals serving long sentences in states with highly indeterminate systems.
• Nationally, back-end factors such as the allocation of sentence credit discounts, and for paroling states, the parole release framework explain more of the variation (60%) of average time served than variation in average sentence length (40%).
• States with identical average sentence length can have different average time served based on the degree of indeterminacy and back-end factors. For example, Oregon and Texas both had an average sentence length of 4.4 years in 2016, yet the average time served in Texas (2.1 years), a state with a high degree of indeterminacy, was lower than in Oregon (3.5 years), a state with a low degree of indeterminacy.

Prior related posts on CCJ's Task Force on Long Sentences:

• Notable CCJ new task force examining long prison terms
• Council on Criminal Justice releases "Long Sentences by the Numbers" 
• Council on Criminal Justice releases "Long Sentences: An International Perspective" 
• Council on Criminal Justice releases Illinois analysis of "The Public Safety Impact of Shortening Lengthy Prison Terms" 
• CCJ releases "Long sentences, better outcomes: Opportunities to improve prison programming"