Convicted felons who receive prison sentences are far more likely to end up back behind bars at a later time than those who were handed probation sentences for similar crimes, a new study published this week in a high-profile journal finds.
The study, titled "The short- and long-term effects of imprisonment on future felony convictions and prison admissions," published in the Proceedings of the National Academy of Sciences journal, shows a causal relationship between sentencing and the likelihood of future incarceration.
"It's the consequence of going into prison and coming out of prison on parole that increases your probability of going to prison again," David Harding of the Haas Institute's Economic Disparities cluster, who co-authored the report along with Jeffrey Morenoff, Anh Nguyen, and Shawn Bushway, said.
"This tells us that the growth of the prison system was in effect, in part, due to the prison system itself and its practices," Harding, an associate professor of sociology at UC Berkeley, added.
"Going to prison increases your probability of going [back] to prison, so there is a sort of vicious cycle as people get trapped in the criminal justice system and go to prison again and again."
Parole is granted to some convicts before the end of their prison terms, while probation is given in place of a prison sentence.
Technical violations and low-level offenses observed during a prisoner's parole through close supervision by authorities was the main reason for their return to prison. By contrast, those sentenced to probation do not receive the same level of scrutiny by their supervisors.
Harding explained that the sentences handed down by judges were often arbitrary and varied significantly, even within the same counties.
The study, which looked at more than 100,000 cases of people imprisoned in Michigan between 2003 and 2006, also finds that prison sentences do little to reduce crime in the long run.
Both prisoners and those sentenced to probation commit about the same levels of crime following the completion of their sentences, the research showed.
"We could potentially be sentencing fewer people to prison, keeping them in the community on probation, and we would save money in the expense of prisons, and be just about as good off in terms of crime, without all the collateral consequences of incarceration for those who are imprisoned," Harding said.
The paper outlines two main policy recommendations. The first is to change the approach to parole violations by, for example, offering treatment to those who have drug and alcohol problems, or changing the nature of the punishment to allow them to remain in their communities.
The second recommendation is to sentence fewer people to prison and more to probation, as the rates for subsequent crimes remained about the same for both groups.