Public order, justice and rights

The Electronic Monitoring of Adult Offenders

“Electronic monitoring represents value for money, providing a cost-effective alternative to custody for offenders who do not pose a risk to the public. However, to ensure that a curfew is effective, it is essential that the contractors and criminal justice agencies work together to ensure that offenders are always tagged promptly and that any breaches of their curfew are dealt with quickly.”

Report cover showing an electronic tracking device

"Electronic monitoring represents value for money, providing a cost-effective alternative to custody for offenders who do not pose a risk to the public. However, to ensure that a curfew is effective, it is essential that the contractors and criminal justice agencies work together to ensure that offenders are always tagged promptly and that any breaches of their curfew are dealt with quickly.”

Sir John Bourn, 1 February 2006


According to the National Audit Office, electronic monitoring of adult offenders provides value for money and a cost effective alternative to custody for low risk offenders. Three months of an electronically monitored curfew are nearly five times cheaper than three months in custody. On average, it costs £1,300 to monitor an offender who has been released from prison on Home Detention Curfew for 90 days compared to £6,500 for the same period in custody. In addition, the use of Home Detention Curfew has reduced pressure on the prison population. NAO testing of the technology used for electronic monitoring showed that it is robust and reliable, detecting absences during curfew periods plus attempts to cut off the tag or tamper with the equipment.

Today’s report to Parliament by the head of the NAO, Sir John Bourn, highlights the number of agencies involved in electronic monitoring, and difficulties they sometimes have communicating with each other and the private contractors who provide the equipment and who actually monitor offenders. The Probation Service, the courts and prisons assess whether an offender is suitable for an electronically monitored curfew and the contractors fit the equipment and monitor the offender. If the offender breaches his or her curfew, courts, prisons, police and the Home Office can be involved in returning the offender to either prison or court. For electronic monitoring to be most effective, co-ordination across the criminal justice system needs to be improved. This will reduce the risk of delays in fitting tags or reporting breaches of curfew and will also make the assessment of offenders more efficient.

The cost of electronic monitoring has fallen considerably since new contracts began in April 2005. The National Offender Management Service could make further savings of up to £9 million a year if it streamlined its assessment process. At present, delays mean that only 59 per cent of the prisoners assessed as suitable for Home Detention Curfew are released as soon as they are eligible. Delays occur because prison governors are waiting for reports from probation or other prisons or for the offender’s criminal record.

The impact of the curfew is undermined if the equipment is not installed on time, or if breaches are not promptly dealt with. Of the 290 cases examined, 90 per cent of curfewees were fitted with a tag within 24 hours of the start of their curfew. Delays were caused by the offender themselves, by late or inaccurate information being sent by prisons and courts, and problems setting up the equipment or getting a telephone line installed.

62 cases of these cases related to the first two months of the new contracts (April and May 2005). The NAO found that only 85 per cent of offenders in these cases were tagged on time, although this performance has since improved. Of the 78 cases examined where Home Detention Curfew had been breached, 35 per cent were not reported to the Home Office by the contractors within 24 hours. The NAO also examined a small sample of 35 cases where Curfew Orders had been breached and found that the contractors had reported only 31 per cent to the courts on time. Such delays can be damaging as the offender may not be electronically monitored during this period (if, for example, he or she has cut the tag off) which increases the risk of further breaches or re-offending. Long delays between a breach and an offender either being returned to court or to prison may also create the impression that offenders can breach with impunity, reducing public confidence in the criminal justice system.

Most of the offenders interviewed for the report believed that being on an electronically monitored curfew had been positive, allowing then to remain with their families and to seek employment, and preventing them slipping back into a criminal routine. Our data suggests that curfewees are less likely to re-offend than offenders in custody or on other community penalties, although further research is required to establish this link.


Publication details:

ISBN: 0102936773 [Buy from TSO]

HC: 800 2005-2006