The Effects of Custodial vs. Non‐Custodial Sentences on Re‐Offending: A Systematic Review of the State of Knowledge
Authors: Villettaz Patrice , Killias Martin , Zoder Isabel 
Published: July 2013

The objective of this Campbell Systematic Review was to assess the relative effects of custodial sanctions (imprisonment) and non‐custodial (“alternative” or “community”) sanctions on re‐offending.By “custodial” we understand any sanction where offenders are deprived of freedom of movement, i.e. placed in a closed residential setting not their home, no matter whether they are allowed to leave these premises during the day or during weekends. Thus, boot camps would be considered “custodial” settings according to the definition adopted here. By “noncustodial”, we mean any form of sanction that does not involve any deprivation of liberty, such as community work, electronic monitoring, financial or suspended custodial sanctions. Thus, the category of non‐custodial sanctions includes a great variety of punishments that have in common to leave the offender in the community rather than putting him into confinement.Studies written in any language and prepared between 1961 and 2002 were considered for inclusion. Although a vast majority of the 23 eligible studies show noncustodial sanctions to be more beneficial in terms of re‐offending than custodial sanctions, no significant difference is found in the meta‐analysis based on four controlled and one natural experiments. The review identified several shortcomings of studies on this subject.2. Abstract2.1 ReviewersMartin Killias, Patrice Villettaz, and Isabel Zoder, Institute of Criminology and Criminal Law, Ecole des Sciences Criminelles, University of Lausanne, CH‐1015 Lausanne, Switzerland. E‐mail: martin.killias@unil.ch, patrice.villettaz@unil.ch, Phone: (0041‐21) 692 46 40, Fax (0041‐21) 692 46 05.2.2 BackgroundThroughout the Western World, community‐based sanctions have become a popular and widely used alternative to custodial sentences. There have been many comparisons of rates of reconviction among former prisoners and those who have served any kind of community sanction. So far, the comparative effects on re‐offending of custodial and non‐custodial sanctions are unresolved, due to many uncontrolled variables.2.3 ObjectiveThe objective is to assess the relative effects of custodial sanctions (imprisonment) and non‐custodial (“alternative” or “community”) sanctions on re‐offending. By “custodial” we understand any sanction where offenders are deprived of freedom of movement, i.e. placed in a closed residential setting not their home, no matter whether they are allowed to leave these premises during the day or during weekends. Thus, boot camps would be considered “custodial” settings according to the definition adopted here. By “noncustodial”, we mean any form of sanction that does not involve any deprivation of liberty, such as community work, electronic monitoring, financial or suspended custodial sanctions. Thus, the category of non‐custodial sanctions includes a great variety of punishments that have in common to leave the offender in the community rather than putting him into confinement.2.4 Search strategyRelevant published and unpublished studies which meet the eligibility criteria have been identified through multiple sources, including abstracts, bibliographies, and contacts with experts in several countries.2.5 Eligibility criteriaRandomized or natural experiments have been considered without exception. Quasi‐experimental studies, i.e. comparisons between former prison inmates and those who served community sanctions, have been included, provided that variables in addition to those found routinely in registers (age, sex and prior record) have been controlled for (such as attitudes, personal or employment history etc.); in the course of the review, this criterion has been relaxed in the sense that studies were considered if more than three potentially relevant independent variables have been controlled for. Studies written in any language and prepared between 1961 and 2002 have been considered for inclusion.2.6 Data collection and analysisA coding protocol has been prepared, following the guidelines of the Campbell Collaboration.2.7 Main resultsAlthough a vast majority of the selected studies (see Table 2, page 29) show noncustodial sanctions to be more beneficial in terms of re‐offending than custodial sanctions, no significant difference is found in the meta‐analysis based on four controlled and one natural experiments.2.8 Reviewers’ conclusionsThe review has allowed to identify several shortcomings of studies on this subject:

Controlled experiments are still rare exceptions, although obstacles to randomisation are far less absolute than often claimed.
Follow‐up periods rarely extend beyond two years. Even in cases of controlled trials where later follow‐up studies might be feasible, periods considered never extended to significant parts of subjects’ biographies.
Despite alternative (and presumably more valid) measures of re‐offending (such as self‐reports), most studies do not include measures of re‐offending beyond re‐arrest or re‐conviction.
In most studies, only the occurrence (prevalence) of re‐arrest or re‐conviction is considered, but not the frequency (incidence) of new offences. Some studies have shown, however, that most offenders reduce offending rates after any type of intervention. Thus, the relevant question may be to what extent they improve differently by type of sanction. Therefore, it is urgent to look in future studies at rates of improvement (or reductions in offending) rather than merely at “recidivism” as such.
Rehabilitation in other relevant areas, such as health, employment, family and social networks, is rarely considered, despite century‐old claims that short custodial sentences are damaging with respect to social integration in these other areas.
No study has addressed the possibility of placebo (or Hawthorn) effects. Even in controlled trials, it is not clear to what extent outcomes that favoured “alternative” sanctions were due to the fact that subjects assigned to noncustodial sanctions may have felt being treated more fairly, rather than to specific effects of “alternative” sanctions as such. Given recent research on neurobiological effects of feelings of fairness (Fehr and Rockenbach, 2003), such a possibility should be envisaged with more attention in future research.
2.9 Sources of supportThis review has been funded by the Swiss National Science Foundation (n° 101411‐101960). Financial support by the Swiss National Science Foundation has not affected the independence of reviewers.