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Produced by the Sentencing Academy

Electronic Monitoring

Peer-reviewed research on the effectiveness and impact of sentences, orders, and requirements.

Jay Gormley, University of Glasgow
Melissa Hamilton, University of Surrey

Published: 18 Sep 2025
Last updated: Sep 2025

Summary

Electronic Monitoring (EM) is a tool used in the criminal justice system to track individuals. This bulletin focuses specifically on EM when imposed as part of a criminal sentence in England and Wales—typically through Suspended Sentence Orders or Community Orders—and evaluates its use, effectiveness, and areas for improvement.

Although EM has been promoted as a way to reduce prison use and reoffending, its application in sentencing remains limited. As of mid-2025, only 3% of individuals serving court orders were subject to EM. Most people monitored electronically are not under court-imposed sentences but subject to other forms of control, such as bail or post-release supervision. EM is available in three formats: radio frequency (RF) for curfews, GPS for exclusion zones and tracking, and alcohol monitoring (AM) for sobriety enforcement.

EM, especially RF monitoring, can reduce reoffending during the period the individual is tagged, particularly when used as a standalone condition. However, there is limited evidence of lasting impact after EM ends, and little is known about the effectiveness of newer technologies such as GPS and AM.

Challenges to effective implementation include outdated technology, poor data integration, and inconsistent availability across regions. Furthermore, EM often serves two competing goals—punishment and rehabilitation—which can create tension in how it is implemented and experienced by those wearing the devices.

Importantly, EM tends to be more effective when paired with supervision and support services, rather than used in isolation. Tailored approaches that account for individual circumstances, such as employment, family responsibilities, and rehabilitative needs, can enhance compliance and improve long-term outcomes.

Electronic Monitoring can be used as part of a Community or Suspended Sentence Order.

This Bulletin focuses on the effectiveness of electronic monitoring (EM) in England and Wales and reviews available data on usage trends, highlights practical and operational challenges, and summarises recent research on its impact on reoffending. It reviews studies that were published in English in the last twenty years and that address aspects of the effectiveness of EM when used in sentencing.

EM is increasingly seen as a tool that could reduce reliance on imprisonment, especially for individuals who can be safely supervised in the community. EM involves attaching a tag—usually worn around the ankle—that allows officials to track a person’s location and monitor their compliance with court-ordered rules. If someone breaches a condition, the system sends an alert to a monitoring centre, so police or probation officers can respond. Authorities use EM across a range of situations: as part of a criminal sentence, as a condition of bail, after prison release, or in managing cases involving domestic abuse or terrorism concerns (Masoud, Mahmoud, and Sadegh, 2024). This Bulletin focuses on how EM is used as part of sentencing court orders (i.e., Community Orders or Suspended Sentence Orders).

Currently, EM in England and Wales is delivered in three main forms (Bowen, 2021):

  • Radio Frequency (RF): Typically used to monitor whether a person is at a required location (usually their home) to enforce curfews. This was introduced in 1999.
  • Global Positioning System (GPS): Used to track movements in real time, enforce exclusion zones, monitor curfews, or confirm attendance at appointments. This technology became available in 2018.
  • Alcohol Monitoring (AM): Detects alcohol use by measuring alcohol levels in a person’s sweat. Introduced in 2020, this form of EM supports court-ordered restrictions on alcohol consumption.

HM Prison & Probation Service oversees the national EM system, although it outsources most of the equipment, technology, and daily monitoring to private suppliers (Davies, 2022).

EM can be imposed as part of a court order at sentencing, provided the technology is available in the area and any required consents are given. EM becomes mandatory when the sentence includes a curfew or exclusion requirement, unless the court finds it inappropriate for that specific case (Schedule 9 to the Sentencing Act 2020). The duration depends on the type of monitoring: RFand GPS can be used for up to two years, while AM is limited to 120 days (Sentencing Council for England and Wales, 2025).

Policymakers see EM as a vital tool for reducing prison use while expanding the alternatives to immediate imprisonment available to courts and probation staff (Gauke, 2025). EM is also expected to lower costs by offering a community-based alternative to incarceration (Malthouse, 2022). In practice, EM works by shaping behaviour: requiring people to stay home during certain hours, avoid prohibited areas, or abstain from alcohol (Bowen, 2021). These restrictions can be used to support rehabilitation by encouraging a more stable lifestyle, promoting treatment or counselling, restoring family contact, and discouraging association with criminal peers (Scottish Government, 2019, p. 5).

EM remains rarely used as part of criminal sentencing

As of June 2025, only 3,427 individuals were fitted with an EM device through a court-imposed sentence (Ministry of Justice, 2025a). This figure represents just 14% of all people monitored electronically by the probation service and only 3% of the 107,640 individuals serving court orders (Ministry of Justice, 2025b).

Figure 1: Number of individuals fitted with electronic monitoring devices as part of their sentences1

Source: Ministry of Justice, 2025a

As Figure 1 indicates, the current use of EM in sentencing is most common for alcohol detection and least likely for location tracking. Yet, this breakdown has not been consistent over time, likely because of the different time frames for which each type of monitoring was deployed, as well as technological developments and implementation issues. Since its inception, RF monitoring has decreased, while both GPS and AM tagging have increased in use (Ministry of Justice, 2024b). Overall, from mid-2020, when all three types were available for sentencing, the total number of sentenced individuals fitted with EM devices decreased from about 4,500 to 3,000, largely because of the reduced use of RF (Ministry of Justice, 2024b).

The above figures suggest that EM has yet to play a substantial role in sentencing practice, despite its potential to support rehabilitation and/or community-based alternatives to imprisonment. An “EM Expansion Programme” is now underway, designed to ‘build the evidence base for the impact of tagging on reoffending and offenders’ diversion from prison’ (HM Prison & Probation Service, 2023: p. 2).

There are geographical differences in the use of EM. Figure 2 provides rates based on population size per 100,000 of fitting EM devices on those serving Suspended Sentence Orders or Community Orders by region (Ministry of Justice, 2024a).

Figure 2: Rate of EM use by region for the year ending March 2024

Source: Ministry of Justice, 2024a

There are clear regional differences in the deployment of EM devices in court orders, with rates ranging from 3 to 7 cases for every 100,000 people in their population. These differences may reflect not only variations in offending rates across regions, but also that electronic monitoring is more readily available in some areas than in others.

Certain aspects of the demographic profile have remained fairly consistent. Over the last five years, almost 90% of those with EM tags fitted with court orders were male and almost half were between the ages of 30-49 (Ministry of Justice, 2024a). Data on race/ethnicity were not available.

Studies on reoffending in England and Wales

A common, although imperfect, way to judge the effectiveness of sentencing is to compare reoffending rates (Gormley, Hamilton and Belton, 2022). Brunton-Smith (2025a) examined the impact of the RF (radio frequency) form of EM on reoffending rates for individuals with curfew requirements that were part of Community Orders or Suspended Sentence Orders in England and Wales in the year ending March 2017. By comparing individuals with RF EM to statistically similar persons without it, the study found that RF EM was associated with lower reoffending rates. For example, within 12 months, 40% of those on Community Orders with RF EM reoffended, compared to 51% without it. Reoffending was notably lower during the first few months of monitoring, which aligns with the typical duration offenders wore the EM tags.

In a follow-up that expanded the scope of analysis and period of study from 2014-2018, Brunton-Smith (2025b) shows that RF EM helps reduce reoffending during the EM monitoring period and across the entire sentence. For example, reoffending rates during monitoring were lower for Community Orders (17% vs. 22%) and Suspended Sentence Orders (15% vs. 18%). RF EM also improved compliance with probation requirements, reducing breaches, and increasing completion of other sentence conditions. However, the study found little evidence of a lasting effect after electronic monitoring ends, with reoffending rates post-sentence being similar for Community Orders and slightly lower for Suspended Sentence Orders. In addition, the impact of RF EM appeared to vary by the type of offence (being more effective for offences like theft and robbery), although it is unknown why this was the case.

By contrast, Lightowlers examined data on alcohol abstinence monitoring requirements and found ‘successful completion of an abstinence requirement was less likely for those serving sentences for theft offences’ (Lightowlers, 2024: p. 3). The reasons for this are unknown, although the author postulates that theft may fund alcohol use or relate to income or homelessness. Encouragingly, Lightowlers did find a significant reduction in the likelihood to reoffend in terms of likelihood and frequency of reappearing before the court. However, the author warns that more research is needed to understand under what conditions and for what type of individuals the abstinence requirement is most effective (Lightowlers, 2024).

Utilising Electronic Monitoring at Sentencing

A common theme across studies is that EM alone will not have a significant impact on encouraging long-term desistance from crime (Belur et al., 2020). Instead, the value of EM in reducing the risk of reoffending is more likely when combined with other supports, such as rehabilitation-focused supervision, positive interactions with supervisory officers, and opportunities for skills development, to maximise compliance and desistance (Graham and McIvor, 2015).

EM, as used in England and Wales, is often highly structured, with potentially greater benefits if used more flexibly (Hucklesby and Holdsworth, 2016). Examples of creativity and flexibility include the following:

  • Tailoring to individual circumstances: Electronic monitoring should consider the wearer’s employment, childcare responsibilities, family dynamics, and victim perspectives to ensure restrictions are workable and effective.
  • Blending monitoring with support: Combining electronic monitoring with probation supervision and rehabilitative interventions is more effective than standalone orders, as it promotes desistance and minimises inefficiencies.
  • Flexibility and responsiveness: Probation officers should have the power to adjust monitoring conditions based on changing circumstances, such as employment shifts or victim needs.
  • Promoting procedural fairness: Clear communication, respectful treatment, and responsive adjustments to restrictions improve wearers’ perceptions of fairness, fostering compliance and cooperation. (Bowen, 2021).

Together, these strategies offer a pathway for improving the design and impact of EM, moving it beyond simple surveillance and toward a more integrated, supportive tool for reducing reoffending.

Why Electronic Monitoring can fail

EM faces a distinct set of challenges that limit its effectiveness as a sentencing tool.

First, weaknesses in breach detection and enforcement may undermine deterrent and incapacitation aims. Third-party providers, responsible for the technology and systems behind EM, frequently fail to deliver timely information about breaches, limiting the system’s ability to intervene quickly and effectively (HM Inspectorate of Probation, 2025). The probation service has recommended improving real-time monitoring capabilities and enhancing coordination between police and probation teams (Gauke, 2025), but this will need to be re-evaluated in the future.

Second, concerns remain about the effectiveness of EM (National Audit Office, 2022, para.18). Despite years of investment, implementation has been hampered by delays in delivering a functional case management system, reliance on outdated technology, and poor integration of data systems across multiple suppliers (Davies, 2022). These shortcomings have constrained the development of EM as a reliable alternative to custody. Without modern infrastructure and high-quality data, EM struggles to support effective supervision or evidence-based decision-making.

Finally, EM, when used in sentencing, straddles two different goals: punishment and rehabilitation (Gauke, 2025). While EM may achieve both these goals, an electronic device on its own is unlikely to support offender rehabilitation and reintegration. Thus, if the focus is only on punishment, insufficient attention may be paid to other objectives (Nellis, 2015).

Data Limitations

The evidence base for EM is surprisingly underdeveloped. The National Audit Office has noted that the ‘lack of focus on monitoring benefits and continued poor evidence base means that… Parliament still does not have a clear view on what it has achieved or whether electronic monitoring is an effective intervention’ (National Audit Office, 2022, para. 17). The Brunton-Smith (2025a, 2025b) findings suggest that RF EM can help reduce reoffending, particularly due to its situational impact during the period the persons were subject to EM. While valuable, these studies did not address the other two forms of EM (GPS and AM) and are now somewhat dated in terms of various aspects of the EM system having changed in more recent years (including the decreasing use of RF and increasing deployment of GPS).

Alcohol monitoring specifically appears to be effective in terms of high compliance rates, whereby AM devices did not register a tamper or alcohol alert on 97% of the days worn since the initiation of the technology in 2020 (Ministry of Justice, 2024a). However, data is not available to show whether there is any impact on longer-term abstinence or alcohol-related reoffending (Davies, 2022). (See our bulletin on Alcohol Monitoring.)

In this bulletin, we do not include reoffending statistics for EM used at other stages of the criminal justice process, such as during pretrial release or post-prison supervision. The relationship between EM and reoffending appears to differ significantly in these other contexts (Renzema and Mayo-Wilson, 2005). Moreover, studies that focus on or combine these other uses of EM tend to produce mixed results, making it difficult to draw clear or reliable conclusions (Belur et al., 2020).

Data from other jurisdictions may offer some general insights on the potential for improving the use of EM, but must be treated with the utmost caution, as the systems may operate differently from those in England and Wales. For example, a reduction in reoffending rates for EM-based community sentences compared to prison sentences was found in a study in Sydney, Australia, which included a few controls and a 10-year follow-up period (Williams and Weatherburn, 2022). Yet, it is not possible to say if the same result would occur in England and Wales. A similarly long follow-up period for studies in England and Wales is needed.

Finally, more data is needed on offenders’ experiences of EM. On the one hand, EM can impose significant restrictions on liberty and can be experienced by many as burdensome. A synthesis of studies internationally found that individuals subject to EM (whether as part of their criminal sentence or not) reported stigma when the tag is visible, emotional strain from constant surveillance, reduced job prospects, and family conflict arising from compliance requirements (Howard, 2018). On the other hand, some report that EM helped them avoid negative influences, reconnect with family, or access work and training opportunities (Vanhaelemeesch, Vander Beken & Vandevelde, 2014). As such, how EM is experienced may depend on a range of factors, including its duration, the level of restrictiveness, and individual circumstances. More data is needed to determine when and why tags work best.

Conclusion

Electronic monitoring holds clear promise as a tool to support community-based sentencing, potentially reducing prison use, encouraging compliance, and promoting offender rehabilitation and reintegration into the community. However, its current role in sentencing practice remains limited. While research shows that EM can reduce reoffending during the monitoring period, data on its long-term effectiveness is limited. Outdated systems, inconsistent use, and a lack of supportive infrastructure hinder the effective use of EM.

This Bulletin is part of a series on the effectiveness of sentencing in England & Wales. Other Effectiveness Bulletins can be found here.

For further information, contact Annalena Wolcke at a.wolcke@sentencingacademy.org.uk

References

  1. The sums of the three options are greater than the overall figure subject to EM because an individual could be sentenced to more than one type of EM simultaneously, such as location monitoring (RF) and alcohol monitoring (AM) (Schedule 9 to the Sentencing Act 2020). ↩︎