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May 19, 2009

Interesting deterrence study out of Italy (perhaps providing a basis for more clemencies)

This new press release from Science Daily, titled "Potential Criminals Deterred By Longer Sentences," reports on an interesting new published study on deterrence coming from Italy.  Here are excerpts from the press release:

A new study published in the Journal of Political Economy sheds some empirical light on the question of deterrence.  Using a recently passed Italian law as a natural experiment, the study found that former prisoners are less likely to return to jail if they expect longer sentences for future crimes....

Passed in 2006, Italy's Collective Clemency Bill presents a unique opportunity to study the deterrent effect of prison sentences, the authors say.... When the clemency bill was passed, it immediately released thousands of prisoners who had three years or less left on their sentences.  The remainder of each prisoner's sentence was suspended, but not forgiven.  The law stipulated that a former inmate who commits a new crime within five years will have the suspended portion of his sentence reinstated and added to the sentence for the new crime.  As a result, a repeat offender can expect extra jail time equal to the suspended portion of his sentence — anywhere from one month to three years.

Using government data, the researchers looked at the recidivism rates of these former inmates for the first seven months after their release. They found that those with longer suspended sentences — and therefore longer expected sentences for new crimes — were less likely to be re-arrested than those with shorter suspended sentences....

The deterrent effect was consistent across age groups, and among men and women, though 95 percent of the sample was male. "This means that a policy a commuting actual sentences in expected sentences significantly reduces recidivism," Dr. Vertova says. "A mass release of prisoners can be effective in reducing their propensity of re-committing crimes if, when a released individual gets convicted of a new crime, his normal sentence is increased by the time that was pardoned because of the early release."

There was one important exception to the deterrent effect, however.  Recidivism rates among those whose original crime was more serious were essentially unaffected by the length of their suspended sentence.  That finding suggests that "more dangerous inmates are not deterred," the authors write.  The researchers also caution that their results only measure deterrence on those who have already served time in jail. "Indeed, it is not clear whether these results can be to individuals who have never received prison treatment."

The full study can be accessed at this link, and here is the paper's official abstract:

The Collective Clemency Bill passed by the Italian Parliament in July 2006 represents a natural experiment to analyze the behavioral response of individuals to an exogenous manipulation of prison sentences.  On the basis of a unique data set on the postrelease behavior of former inmates, we find that 1 month less time served in prison commuted into 1 month more in expected sentence for future crimes reduces the probability of recidivism by 0.16 percentage points.  From this result we estimate an elasticity of average recidivism with respect to the expected punishment equal to −0.74 for a 7‐month period.

The implications of this interesting study are potentially quite profound, especially at a time when states are struggling with over-crowded prisons and academics are debating "second look" sentencing reforms.  This study suggests governments might be able to save money AND reduce the probability of recidivism by granting conditional clemencies to non-violent offenders.

May 19, 2009 at 07:25 AM | Permalink


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Longer Sentences Deter in Italy: Early this morning Doug Berman posted excerpts from a press release describing the results of a new published study on deterrence coming from Italy. The study, "The Deterrent Effects of Prison: Evidence from a Natural... [Read More]

Tracked on May 19, 2009 6:34:47 PM


I assume no deterrence. About half the career criminals are murdered. If deterrence is possible, the arrest deters the normal person. Hurting someone's feelings can deter a crime. Half the perps, half the victims are legally drunk. The other half is highly impulsive. Criminals will not be doing calculation beyond the money for the next fix.

No. Only incapacitation has any effect on crime. The most reliable principle is, the deceased have a low recidivism rate. We should be attritioning the half that is not murdered. Each incapacitation saves $millions in future damages.

Posted by: Supremacy Claus | May 19, 2009 8:48:52 AM

The results are not helpful without comparison to past and subsequent recidivism rates of similar offenders matched on offense type, assessed risk levels, actual original sentence lengths, normal times served, or other relevant variables. The qualifier at the end about "more serious" offenders does manage to hint at this. If you don't know the baseline for comparison, you can't really tell if this is better or worse or the same as regular release programs with offenders of different "seriousness" levels. And 7 months into an unusual program different from normal release programs (the offenders were apparently given specific details as reinforcements at release, but will that recency effect wear off over time???) is a little early to evaluate, which is one reason why 36 months has become the standard and still should be for this study. There really is a study which could prove helpful to policymakers in this, but it doesn't appear to have been done yet.

Posted by: Michael Connelly | May 19, 2009 10:04:27 AM

In the US, the overwhelming majority of incarcerated people would resemble the extreme end of the spectrum in this study. They are the ones who cannot be deterred after multiple convictions. They should all be killed immediately to protect the public.

Posted by: Supremacy Claus | May 19, 2009 9:28:44 PM

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