NHS Health Scotland



C. Evidence for therapeutic services and diversion from prosecution (Enforcement model)


There is highly processed and review-level evidence of the effectiveness of therapeutic services within criminal justice settings in reducing drug use and drug- related crime. As defined in the introduction to this document, Scottish policy directives are also supportive of this approach.


NICE Clinical Guideline 51 general considerations on drug misuse psychosocial interventions include [1]:

  • In order to reduce loss of contact when people who misuse drugs transfer between services, staff should ensure that there are clear and agreed plans to facilitate effective transfer. Routine screening for recent drug use should be offered in mental health and criminal justice settings.
  • For people in prison who have drug misuse problems, access to and choice of treatment should not depend on whether the person is participating in treatment voluntarily or is legally required to do so. And treatment options should be comparable to those available in the community, with additional consideration specific to the prison setting. For example for those who choose to remain abstinent after release from prison, residential treatment should be considered as part of an overall care plan (given known high risk of overdose post-release).

The Advisory Council on Misuse of Drugs’ overview of the evidence on recovery from drug and alcohol dependence cites UK research evidence (Skodbo et al 2007) that coercion can be an effective way of getting people into treatment. [2]

A Scottish review of criminal justice interventions for drug users also concludes that equitable outcomes are achieved for those who access treatment through the criminal justice system as those who access it voluntarily. (Also citing previous work by Hough (1996) which concluded legally coerced treatment was no less effective than treatment entered into voluntarily and evidenced over time by McSweeney et al. (2006).) [3]

In their review of the evidence for supply control, Strang et al. (2012) surmise that although contested the evidence of effectiveness of sanctions such as wide-scale arrests and imprisonment as a deterrent of drug use and related criminal offending is at best weak. However, increasing evidence is cited from criminal justice programmes suggesting ‘specific, brief and immediate sentences (e.g. overnight)’ for individuals who fail drug tests in their supervision orders can produce considerable reduction in drug use and offending. The authors note this evidence comes from mandated abstinence programmes for drug and drink-driving offenders on community release, and programmes for addicted physicians and pilots.

There is review-level evidence that drug courts, as an intervention to support offenders into treatment, are more effective at retaining drug users than other diversion programmes, although the scale-up of such interventions is noted to have been challenging. [4]

Drug courts
Evidence indicates that drug courts are effective in reducing recidivism; the strength of the evidence varies by drug court type with effects smaller in juvenile drug courts. Programmes with eligibility for non-violent offenders only had larger reductions in general recidivism.

Evidence of adult drug courts suggests that participants have reduced recidivism during and after drug court treatment, with effects lasting at least three years. Effectiveness is largely robust to programme variations. However, evidence supporting the importance of leverage and intensity (dismissing charges and more frequent status hearings) were significant in relation to specifically reducing drug-related recidivism. [5]

There is limited evidence from US-based models of family treatment drug courts that these can be effective in supporting parents to enter treatment, stay in longer and complete treatment. Some aspects were less conclusive, such as child welfare results. The basic model includes regular, frequent court hearings, intensive judicial monitoring, timely substance abuse treatment and other needed services, frequent drug testing, and rewards and sanctions linked to parental compliance with their service plan when the primary motivation for parents involved in FTDCs is the goal of being reunited with their children. Findings from a large-scale prospective study (Worcel et al., 2008) indicate that FTDCs did not decrease children’s stays in out of home placement, but they did increase the likelihood of the family being reunited. Clarity is needed as to whether this positive outcome is a result of the model’s influence on treatment or whether the model uniquely contributes to family reunification. [6]


Drug treatment
The Best et al. (2010) Scottish-Government-commissioned review cites evidence from a meta-analysis of drug treatment studies (Prendergast et al., 2002) that concludes drug abuse treatment is effective in reducing both drug use and offending. This review suggested that the younger the age of treatment participants the better predictor of reductions in crime. [7]

There is evidence of effectiveness from multiple seminal large-scale longitudinal treatment outcome studies that treatment for drug dependence works to reduce drug use, improve mental and physical health, and reduce levels of crime [for a summary of findings see Best et al. (2010)]. Findings from these multiple ‘what works in practice’ studies at two to five years follow-up suggest a minimum three months treatment duration is critical to contributing to successful outcomes.

  • The UK National Treatment Outcome Research Study, economic analysis at two years follow-up [8] suggests the majority of calculated economic benefits associated with treatment are accounted for by reductions in criminal behaviour from reduced heroin use.
  • Analysis of criminal activity at five years follow-up [9] suggests that crime reductions are statistically significant and represent substantial changes in behaviour and have considerable personal, social and clinical importance.


The Drug Treatment Outcomes Research Study (DTORS) is a major national longitudinal evaluation of drug treatment in England. Participants were recruited from treatment facilities between February 2006 and March 2007. Findings suggest  evidence of treatment effectiveness with significant and substantial reduction in drug use and offending, with the criminal justice system (CJS) an equally valid route into drug treatment, with few differences in outcomes compared to non-CJS referrals. In addition, when the net gains in health from drug treatment and the savings in crime-related costs as a result of reduced offending were calculated, treatment was cost-effective and cost-beneficial. [10]



  1. National Institute for Health Care Excellence (NICE, 2011) Clinical Guidelines 51: Drugs Misuse: Psychosocial Interventions. London: NICE.

  2. Advisory Council on Misuse of Drugs (ACDM, 2012) Recovery from drug and alcohol dependence: an overview of the evidence. London: ACDM.

  3. Malloch, M. (2011) Interventions for Drug Users in the Criminal Justice System: Scottish Review. Glasgow: The Scottish Centre for Crime and Justice Research.

  4. Strang, J,. Babor, T. Caulkins, J. Fischer, D. Humphreys, K. (2012) Drug policy and the public good: evidence for effective interventions. Addiction 2 Series. The Lancet, p379.

  5. Mitchell, O. Wilson, D. B. Eggers, A. MacKenzie, D. L. (2012) Assessing the effectiveness of drug courts on recidivism: A meta-analytic review of traditional and non- traditional drug courts. Journal of Criminal Justice. pgs40:60–71.

  6. Mitchell, F. Burgess, C. (2009) Working with families affected by parental substance misuse: a research review. Edinburgh: Scottish Child Care and Protection Network, Scottish Government.

  7. Best, D. Rome, A. Hanning, K.A. White, W. Gossop, M. Taylor, A. Perkins, A. (2010) Research for Recovery: A Review of the Drugs Evidence Base. Edinburgh: Scottish Government.

  8. Godfrey, C. Stewart, D. Gossop, M. (2004) Economic analysis of costs and consequences of the treatment of drug misuse: 2-year outcome data from the National Treatment Outcome Research Study (NTORS).

  9. Gossop, M. Trakada, K. Stewart, D. Witton, J. (2005) Reductions in criminal convictions after addiction Tx: 5-year follow up. Drug and Alcohol Dependence.

  10. Donmall, M. Jones, A. Davies, L. Barnard, M. (2009) Summary of Key Findings from the Drug Treatment Outcomes Research Study (DTORS). London: Home Office Research Report 23.