The importance of early detection and diversion of mental ill offenders to avoid prison sentences


‘Diversion’ /early intervention with offenders can be away from the justice system or can be within the justice system in the United Kingdom, e.g. the issuing of community sentence with some health support. This suggests a fairly obvious economic case for diversion, as there appears to be a double benefit: community sentences almost invariably cost less and they have better offending outcomes.

Comparison of re-offending rates needs to be on a like-for-like basis, i.e. the characteristics of offenders in the two groups may be significantly different. The Ministry of Justice (MOJ) in England use a technique called Propensity Score Matching that matches offender and takes account of characteristics such as age, gender, offence type, offence severity and number of previous offences1.

Analysis on this basis shows that there is still a difference in re-offending rates between offenders after matching receiving short prison sentences and those receiving community sentences.

The numbers who re-offend are lower by a tenth, the number of re-offences is lower by more than a quarter and the number of offenders sent to prison for re-offending is lower by a similar amount. Particularly when set against the very high long-term costs of re-offending after release from prison, these figures give strong support on economic grounds to a general policy of diversion.

One type of community sentence available to sentencers in the UK is an order which includes a requirement for mental health treatment and a financial analysis carried out a review of diversion in England calculated that mental health support for a community sentence is around £4,3002 .

Key features of a community sentence including a mental health treatment requirement are:

• sentencers with an option for diverting lowlevel offenders with mental health problems away from prison but not from a justice sanction altogether.

• it ensures that appropriate packages of mental health treatment are made available in the community.

• compliance with treatment is monitored for a specified period.

All of these features are also central to the working of mental health courts, a mechanism for diversion which is increasingly widely used in the US and on which there is now a significant body of research, albeit of varying quality. A recent quantitative review of this literature combines the findings from 18 separate studies and concludes that mental health courts are an effective and cost-effective intervention3. In particular, they are successful in linking individuals to mental health treatment, they reduce re-offending and they can demonstrate some improvement in a range of clinical outcomes. The overall impact on offending is summarised in an effect size of 0.54. (an effect size of around 0.2 is regarded as ‘small’, one of around 0.5 is ‘medium’ and one of around 0.8 is ‘large’.)

Another American study combines the results from a number of published research studies and comes to the strongly positive conclusion that every $1 invested in mental health courts, including the associated costs of treatment, yields benefits to society valued at $6.76. All the benefits take the form of lower costs of crime associated with reduced reoffending, with 25% of these savings accruing to taxpayers and 75% to the rest of society (mainly those who would otherwise have been the victims of crime). The costs of mental health courts and associated treatment packages are put at around $3,000 per offender4.

Another mechanism for diversion is provided by the Intensive Alternatives to Custody (IAC) pilot programme which ran from 2008/09 to 2010/11 in England, testing the use of intensive community orders in diverting offenders from short prison sentences. IACs are not designed specifically for offenders with mental health problems but have a clear application. An IAC order is a comprehensive community-based intervention focusing on reducing the risk of re-offending. Orders lasted 12-24 months, the cost of a completed order was around £5,550. In comparison, the estimated annual cost of a prison place is estimated at around £40,000 a year. The MOJ noted that IACs would break even compared to 45 days in custody (the time served for an average three-month short custodial sentence) if they reduced the probability of re-offending by only a small amount5. Another study estimated that IACs could reduce re-offending by 13% compared with short custodial sentences6. Relating this to cost-ofcrime data, it is estimated that the economic value of reduced re-offending works out at around £19,000 per offender, measured over a five-year period. Also taking into the account the lower cost of IACs relative to most short custodial sentences, these figures suggest a good economic case for diversion on this model.

As a final point, it is important to emphasise that the diversion of offenders from prison to the community is not an end in itself but rather a means of promoting better outcomes in relation to offending, mental health and related needs. This in turn requires that offenders who are diverted actively engage with appropriate services and interventions and also that these programmes are evidence-based in relation to their effectiveness and cost-effectiveness. As noted in an another study7 particularly highlights the need for engaging the offender as a key activity by adopting a pro-active and assertive approach.

Equally important is that clients engage with interventions that have a good track record in terms of effectiveness and value for money4,8.

The following have been identified as good value for money:

Young offenders:

— Functional family therapy.

— Aggression replacement training.

— Multi-dimensional treatment foster care.

— Drug courts.

— Victim offender mediation (i.e. restorative justice).

Adult offenders:

— Cognitive behavioural treatment.

— Employment training/job assistance in the community.

— Intensive supervision (surveillance and treatment).

— Case management with sanctions for substance misusing offenders.

— Therapeutic communities for offenders with comorbid substance misuse and mental health disorders.

short, putting into practice what we know that works and stop doing what doesn't.


Sean Duggan Chief Executive at Centre for Mental Health



1. Ministry of Justice. 2013 compendium of reoffending statistics and analysis. Ministry of Justice, Statistics Bulletin [Internet]. London: Ministry of Justice; 2013 [cited 2015 dec 8]. Available from: https://www.gov.uk/government/ uploads/system/uploads/attachment_ data/file/278133/compendium-reoffendingstats- 2013.pdf.

2. Tribal Group. Financial support to the Bradley Review. Forthcoming 2008.

3. Sarteschi C, Vaughn M, Kim K. Assessing the effectiveness of mental health courts: a quantitative review. Journal of Criminal Justice. 2011; 39: 12-20.

4. Washington State Institute for Public Policy [Ìnternet]. Whashinton: WSIPP; c1990-2016. Benefit- cost results; [ about 10 screens] Available from: http://www.wsipp.wa.gov/BenefitCost.

5. Ministry of Justice. Evaluation of the Intensive Alternatives to Custody pilots. Research Summary 3/11 [Internet]. London: Ministry of Justice; 2011 [cited 2015 dec 19]. Available from: https://www.gov.uk/government/ uploads/system/uploads/attachment_data/file/217372/intensive-alt-custody-researchsummary.pdf.

6. Matrix Knowledge Group [Internet]. Final report: an economic analysis of alternatives to short-term custody.London: Matrix Evidence; 2012 [cited 2015 Nov 4]. Available from: http:// www.matrixknowledge.com/vendor/wp-content/ uploads/2013/09/27-Matrix-MJW_updated- Final-Report_June-2012-2.pdf

7. Durcan G. Keys to Diversion: Best practice for offenders with multiple needs[Internet]. London: Centre for mental Health; 2014 [cited 2015 Nov 27]. Available from: http://www.centreformentalhealth. org.uk/keys-to-diversion

8. Social Research Unit [Internet]. Dartington: The Social Research Unit; 2014. Investing in children; [about 2 screens] Available from: http:// investinginchildren.eu/.


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