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.