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"Smart people (like smart lawyers) can come up with very good explanations for mistaken points of view."

- Richard P. Feynman, Physicist

"There is a danger in clarity, the danger of over looking the subtleties of truth."

-Alfred North Whitehead

August 30, 2010

Deterrence Effect Weak

Deterrence is often used as a justification for increased punishment for criminal acts. From a law and economics perspective, the expected punishment for a criminal act is the product of the chance of being arrested and convicted and the punishment meted-out after a conviction. Increasing criminal penalties is one way the expected punishment for a crime can be increased. The other way is by increasing the chance of arrest and conviction.

However, increasing expected punishment can theoretically reduce crime in two ways. The first way that crime may decline with an increase in expected punishment is through deterrence. Individuals, who would otherwise commit a crime with a lower expected punishment, modify their behavior and not commit the crime due to the increase in expected punishment. They decide the cost of the crime is too high compared to its benefits.

The second way crime is reduced through an increase in expected punishment is through incapacitation. If individuals who would otherwise commit crimes are convicted and incarcerated, then the number of crimes committed should decline because the individual’s circumstances prevent them from committing the crime. Separating incapacitation effects from deterrence effects provides a methodological challenge to researchers.

A recent meta-analysis of the research on deterrence found that the deterrent effect is small, especially when one looks at the more rigorous studies. Specifically, the deterrence effect from greater punishment is small to non-existent and deterrence from the certainty of punishment slightly larger. [i]

One researcher of criminal deterrence is Steven D. Levitt of the University of Chicago and Freakonomics fame. In two research papers, Levitt provides support for deterrence under certain circumstances. Levitt, in a procedurally innovative study, concluded that increasing arrest rates lead to a reduction in crime and the reduction from deterrence was greater than that from incapacitation, especially for property crimes.[ii] By increasing the chances of arrest, one may increase deterrence. The findings in this study do not address increased penalties on changes in crime due to deterrence.

In a second research paper, Levitt examined the differential of punishment between juvenile and adult criminal justice systems in various states. Levitt concluded that the increased penalties in the adult criminal justice system reduced crime. The deterrence effect was almost twice as great for violent crimes compared to property crimes. In situations where defendants have reason to know and understand the differential of criminal penalties, deterrence is present. (Incidentally, he further concluded that there was not a strong relationship between the punitiveness of the juvenile justice system and a juvenile defendant’s involvement in crime as an adult.) [iii]

If deterrence is not effective, then prison sentences that exceed those required to address incapacitation needs and just deserts for the crime, may be a waste of societal resources. If deterrence is effective, then such sentences may reduce overall societal crime. However, it appears that deterrence effect is small, if it exists at all, and depends on the individual case.

The reason deterrence may not be as effective under many circumstances involves some basic psychological principles of human behavior and behavior modification. I will discuss that research in my next entry.

[i] Pratt, Travis C., Francis T. Cullen, Kristie R. Blevins, Leah E. Daigle, and Tamara D. Madsen, 2006, “The Empirical Status of Deterrence Theory: A Meta-Analysis” pp 3670370 in: Taking Stock: The Status of Criminological Theory, Francis Cullen et al, editors, Transaction Publishers.

[ii] Levitt, Steven D, 1998, “Why do Increased Arrest Rates Appear to Reduce Crime: Deterrence, Incapacitation, or Measurement Error”, Economic Inquiry, Jul 1998, pp. 353-372.

[iii] Levitt, Steve D., 1998, “Juvenile Crime and Punishment,”, Journal of Political Economy, vol. 106 No. 6 pp 1156-1185.

The views expressed in this blog are solely the views of the author(s) and do not represent the views of any other public official or organization.


  1. Of course the death penalty deters.
    Dudley Sharp

    All prospects of a negative outcome deter some. It is a truism. The death penalty, the most severe of criminal sanctions, is the least likely of all criminal sanctions to violate that truism.

    1) 27 recent studies finding for deterrence, Criminal Justice Legal Foundation

    2) "Deterrence & the Death Penalty: A Reply to Radelet and Lacock"

    3) "Death Penalty, Deterrence & Murder Rates: Let's be clear"

    4) This is out of date, but corrects a number of the misconceptions about deterrence.

    "Death Penalty and Deterrence"

    5) "The Death Penalty: More Protection for Innocents"

  2. Of course the death penalty deters. A review of the debate.
    Dudley Sharp

    1) Anti death penalty folks say that the burden of proof is on those who say that the death penalty deters. Untrue. It is a rational truism that all potential negative outcomes deter some - there is no exception. It is the burden of death penalty opponents to prove that the death penalty, the most severe of criminal sanctions, is the only prospect of a negative outcome that deters none. They cannot.

    2) There have been 27 recent studies finding for death penalty deterrence. A few of those have been criticized. The criticism has, itself been rebutted and/or the criticism doesn't negate no. 1 or nos. 3-10.

    3) No deterrence study finds that the death penalty deters none. They cannot.

    4) About 99% of those murderers who are subject to the death penalty do everything they can to receive a lesser sentence, in pre trial, plea bargains, trial, in appeals and in clemency/commutation proceedings. Life is preferred over death. Death is feared more than life. No surprise. Would a more rational group, those who choose not to murder, also share in that overwhelming fear of death and be deterred by the prospects of execution? Of course.

    5) There are a number of known cases of individual deterrence, those potential murderers who have stated that they were prevented from committing murder because of their fear of the death penalty. Individual deterrence exists.

    6) General deterrence exists because individual deterrence cannot exist without it.

    7) Even the dean of anti death penalty academics, Hugo Adam Bedau, agrees that the death penalty deters .. . but he doesn't believe it deters more than a life sentence. No. 4, above, provides overwhelming anecdotal evidence that the death penalty is a greater deterrent than a life sentence. In addition, the 27 studies finding for deterrence, find that the death penalty is an enhanced deterrent over a life sentence.

    8) All criminal sanctions deter. If you doubt that, what do you think would happen if we ended all criminal sanctions? No rational person has any doubt. Some would have us, irrationally, believe that the most severe sanction, execution, is the only sanction which doesn't deter.

    9) If we execute and there is no deterrence, we have justly punished a murderer and have prevented that murderer from ever harming/murdering, again. If we execute and there is deterrence, we have those benefits, plus we have spared more innocent lives. If we don't execute and there is deterrence, we have spared murderers at the cost of more innocent deaths.

    10) Overwhelmingly, people prefer life over death and fear death more than life.

    "If we execute murderers and there is in fact no deterrent effect, we have killed a bunch of murderers. If we fail to execute murderers, and doing so would in fact have deterred other murders, we have allowed the killing of a bunch of innocent victims. I would much rather risk the former. This, to me, is not a tough call." John McAdams - Marquette University/Department of Political Science