Can the use of electronic monitoring reduce demand for prison places? By how much?

Top point

Using risk based selection criteria to reduce the time spent in custody of lower risk offenders sentenced between 1 to 10 years, substituting electronically monitored community supervision, could reduce demand for prison places by about 2500.
Prisoners will generally spend only a proportion of their custodial sentence in prison, the rest of the time being spent in the community under post-release licence and supervision.  Currently, for those on determinate (i.e. fixed length) sentences in England and Wales,  this is set at 50%.

Supervision in the community can take a variety of forms with licence conditions imposing restrictions on what the offender is or is not allowed to do.  Electronic Monitoring (EM), depending on the technology in use, can provide continuous monitoring of an offender's location (and potentially other information such as alcohol or drug use) and so early warning of any non compliance.

Given that EM could provide a more rigorous and more risk assured framework for community supervision, this analysis considers a scenario where an offender serving a medium or long term custodial sentence is released from prison earlier than might otherwise be the case, subject to rigorous monitoring provided by EM.  There is a number of potential advantages of such an approach:

* Pressure on prison spaces is reduced

* Offenders can take advantage of community programmes such as education and training, where relevant receive family or other social or health support,  be available for work and so better manage the transition back to a law abiding life.

The Scenario

In this scenario the eligible group comprises those offenders serving custodial sentences between 12 months and 10 years. (For an illustrative scenario covering short (<12 month sentences see here)

Further, individuals:

* assessed as  high or very high risk of harm are excluded;

*  with more than one offence (i.e. the current one)  are excluded

*  with prison discipline problems resulting in the custody time being extended beyond the (normal)  50% release point are excluded

*  will have served at least 30% of their sentence, and so they will be on post-release licence supervision for the 70% balance of the sentence.

* the intensity of Electronic Monitoring might reduce as the end of the sentence nears

* other conditions would include access to rehabilitative interventions

* breach rates are the same as for those who are released normally

* the change is introduced from Jan 2018

The comments made in the case of diversion from short custody also apply here. Plainly, in a real implementation of  such policy, the risk assessment and safeguards pertaining to individual cases would need to be carefully considered and properly implemented. This scenario is therefore generic, intended to explore the potential impact on numbers in custody and post-release supervision in the community.  Other aspects of this and similar scenarios, e.g. cost benefit and shift of resources that would be needed,  will be explored as separate examples.


The net impact is estimated to be a reduction of the numbers in custody by about 2500; and a similar increase on the number under supervision. This will vary up or down depending on whether some of the selection criteria are made more or less restrictive.

Is this worth considering? Given that this scenario targets offenders who have committed more serious offences, a crucial aspect to a successful scheme of this kind would be appropriate selection of those who would benefit most from the extra time in the community, improving the prospects of rehabilitation, while keeping the risks of further offending low, maintaining overall confidence.

The application of scientific, quantitative methods to questions of policy and practice in criminal justice