The effect of prison on criminal behavior

The effect of prison on criminal behavior PDF Version (11 KB)

Research summary
Vol. 4 No. 6
November 1999


Does increasing the length of time in prison reduce the criminal behaviour of offenders?


Imprisoning individuals who break the law has many goals. Imprisonment shows society's abhorrence for certain antisocial behaviours and incarceration removes individuals from the community for a period of time. Most offenders however, are eventually released from prison. Thus, another goal of incarceration is that imprisonment will serve to deter offenders from engaging in further criminal behaviour.

Across North America, imprisonment has become a fairly common consequence for law violation. Canada's incarceration rate is high relative to other Western industrialised countries, although it trails the United States by a wide margin. Not only is imprisonment used more often, there is also a trend to confine individuals for longer periods of time in prison. It is commonly assumed that longer sentences are more punishing and more likely to deter individuals from further crime. The increased use of imprisonment and longer prison sentences come with significant financial and social costs. The present study examines whether longer sentences reduce recidivism and meet the goal of deterrence.


A quantitative (meta-analytic) review of the research literature was conducted. Fifty studies that examined the effect of imprisonment and longer sentences on recidivism were analysed. The studies described variations in the use of imprisonment and recidivism. To be included in the review the study must report a minimum follow-up period of at least six months. For example, a study may report the recidivism rates for offenders serving short prison sentences compared to offenders serving long prison sentences. In addition, statistical procedures were employed to investigate whether prison had a deterrent effect for offenders who posed different levels of risk to re-offend. For example, is imprisonment and longer sentences more effective for higher risk offenders than for lower risk offenders?


The 50 studies involved over 300,000 offenders. None of the analyses found imprisonment to reduce recidivism. The recidivism rate for offenders who were imprisoned as opposed to given a community sanction were similar. In addition, longer prison sentences were not associated with reduced recidivism. In fact, the opposite was found. Longer sentences were associated with a 3% increase in recidivism.

An analysis of the studies according to the risk of the offender also did not show a deterrent effect. For both low risk and high risk offenders, increasing sentence length was associated with small increases in recidivism. Low risk offenders were slightly more likely to commit new offences than high risk offenders. This finding suggests some support to the theory that prison may serve as a "school for crime" for some offenders.

Regardless of the type of analysis employed, no evidence for a crime deterrent function was found.

Policy implications

  1. For most offenders, prisons do not reduce recidivism. To argue for expanding the use of imprisonment in order to deter criminal behaviour is without empirical support. The use of imprisonment may be reserved for purposes of retribution and the selective incapacitation of society's highest risk offenders.
  2. The cost implications of imprisonment need to be weighed against more cost efficient ways of decreasing offender recidivism and the responsible use of public funds. For example, even small increases in the use of incarceration can drain resources from other important public areas such as health and education.
  3. Evidence from other sources suggests more effective alternatives to reducing recidivism than imprisonment. Offender treatment programs have been more effective in reducing criminal behaviour than increasing the punishment for criminal acts.


For further information

James Bonta, Ph.D.
Solicitor General Canada
340 Laurier Avenue West
Ottawa, Ontario
K1A 0P8
Tel (613) 991-2831
Fax (613) 990-8295

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