Prison Time Served and Recidivism

The relationship between the length of prison terms and recidivism is one of the central points of debate in sentencing and corrections policy. Many people assert that longer prison terms are more effective at deterring future crimes because they set a higher price for criminal behavior and because they hold offenders until they are more likely to “age out” of a criminal lifestyle. Others argue the opposite—that more time behind bars increases the chances that inmates will reoffend later because it breaks their supportive bonds in the community and hardens their associations with other criminals.

The strongest research finds that these two theories may cancel each other out. Several studies, looking at different populations and using varied methodologies, have attempted to find a relationship between the length of prison terms and recidivism but have failed to find a consistent impact, either positive or negative.^[1]

Prison time served

Nationally, from 1990 to 2009, the average amount of time prisoners spent behind bars increased 36 percent, from 2.1 years to 2.9 years.^[2] 

• Prison terms for drug offenders grew at nearly the same rate (36 percent) as those for violent offenders (37 percent) over that period.^[3] 
• The state with the most rapid rise in time served was Florida, with a 166 percent increase.^[4] 
• Michigan had the longest average time served, 4.3 years.^[5] 
• The additional time served by offenders released in 2009, compared with those released in 1990, cost states more than $10 billion.^[6] 

Impact on recidivism and overall crime

Longer prison terms seek to reduce crime through incapacitation and deterrence. Incapacitation is intended to decrease current criminal activity by holding offenders in prison where they cannot commit crimes against the public. Deterrence attempts to prevent future criminal activity, or recidivism, by setting a high enough punishment for the past crimes to dissuade offenders from committing new crimes.

An analysis of data from three states—Florida, Maryland, and Michigan—found little or no evidence that longer prison terms for many nonviolent offenders produced either incapacitation or deterrence effects.  That is, the extra time behind bars neither prevented crimes during the period of incarceration nor kept offenders from committing crimes once released from prison.^[7]

The study found that significant proportions of nonviolent inmates released in these states in 2004 could have served three months to as much as two years less without any decline in public safety, dramatically reducing prison populations and costs:

• Florida:  14 percent of nonviolent offenders could have served shorter sentences, reducing the prison population by as much as 2,600 inmates and saving $54 million.
• Maryland:  18 percent, with reductions of up to 800 and savings of $30 million.
• Michigan:  24 percent, with reductions of as much as 3,300 inmates and savings of $92 million.^[8] 

In sum, for many offenders, longer prison terms boost taxpayer costs but add little to no overall reduction in crime.^[9] 

Public opinion

In national- and state-level opinion surveys, voters overwhelmingly rank reducing recidivism ahead of requiring nonviolent offenders to serve longer prison terms:^[10]

• Nearly 90 percent support shortening prison terms by up to a year for low-risk, nonviolent offenders if they have behaved well in prison or completed programs.^[11]
• More than 80 percent of poll respondents from households in which someone has been a victim of a violent or nonviolent crime agree with the statement “It does not matter whether a nonviolent offender is in prison for 18 or 24 or 30 months.  What really matters is that the system does a better job of making sure that when an offender does get out, he is less likely to commit another crime.”^[12] 

Endnotes