Official Statistics

Technical note

Published 25 April 2024

Introduction

The Electronic Monitoring statistics publication covers the use and delivery of electronic monitoring using curfew devices (radio frequency), location monitoring devices (GPS), alcohol monitoring devices and non-fitted devices (NFDs), for England and Wales. A small number of individuals in the immigration cohort living in Scotland and Northern Ireland are also captured. This document provides more detail on the statistics in this publication and is intended to be used as a guide.

Overview of Electronic Monitoring Statistics

Background

Electronic monitoring supports probation, prisons, courts, the police, the Home Office and the wider justice system in England and Wales. It is a way of remotely monitoring and recording information on an individual’s whereabouts or movements and alcohol consumption, using an electronic device (tag) which is normally fitted to an individual’s ankle. Information about the compliance with an individual’s order is monitored. Electronic monitoring may be used:

• as a condition of court bail;

• as a requirement of a court sentence, primarily community orders and suspended sentence orders;

• for Home Detention Curfew;

• as a licence condition following release from custody;

• as a condition of immigration bail, managed by the Home Office; or

• to intensively monitor a small number of individuals including: some of the highest risk offenders managed under Multi-Agency Public Protection Arrangements (MAPPA); those granted bail by the Special Immigration Appeals Commission (SIAC); and those made subject to Terrorism Prevention and Investigation Measures (TPIMs).

Electronic monitoring was first introduced in 1999 to monitor compliance with curfews using radio frequency (RF) devices, where curfew is the only requirement, these continue to be used. The service was expanded from November 2018 to introduce satellite enabled location monitoring devices. The devices use GPS technology which can record an individual’s movements 24 hours a day. Roll out was fully completed in March 2021 with the provision of location monitoring for under 18s.

GPS devices provide additional functionality, allowing the monitoring of:

• compliance with exclusion zones;

• attendance at a required activity or appointment;

• an offender’s whereabouts, known as trail monitoring. This can provide Probation Practitioners with data about an individual’s whereabouts to support rehabilitative conversations. The Police Courts and Sentencing Act 2022 introduced this for Youth Rehabilitation Orders (this is not available for court bail).

• multiple conditions or requirements if necessary, such as a combination of exclusion zones, curfew, monitored attendance and trail monitoring.

Since 2021 HMPPS has expanded the use of GPS devices for the following offender cohorts:

• acquisitive crime: From April 2021, they have been used as a licence condition for some adult offenders convicted of an acquisitive crime as their principal offence and who have received a custodial sentence of 12 months or more and been released on licence. In late October 2022 this was expanded to those who had received a custodial sentence of 90 days or more. This is currently being piloted by 19 police forces.

• several small pilots for specific offender cohorts, such as Licence Variation, GPS Youth Rehabilitation, and Domestic Abuse Perpetrators on Licence.

• immigration expansion: The Immigration Act 2016 introduced a duty on the Home Office Secretary of State to impose an electronic monitoring condition on Foreign National Offenders (FNOs) and other non-UK citizens subject to deportation proceedings. Following this, in August 2021, HMPPS began using GPS monitoring for those individuals who had been released from prisons or Immigration Detention under ‘Immigration Bail’ on behalf of the Home Office. This was extended to Scotland from 31 August 2022 and Northern Ireland in December 2022. The Home Office also commenced a pilot in June 2022 to impose an electronic monitoring condition of immigration bail to non-FNO asylum claimants who arrive in the UK via unnecessary and dangerous routes. This pilot concluded in December 2023.

Electronic monitoring using a non-fitted device was introduced in November 2022 for the immigration cohort. These devices utilise periodic biometric verification as an alternative to using fitted GPS devices. Those with a non-fitted device have been included within the GPS cohort for the purposes of this analysis.

Alcohol monitoring was introduced to courts in Wales in October 2020 and expanded to courts in England on 31 March 2021 to support the new community sentencing option, the Alcohol Abstinence and Monitoring Requirement (AAMR). An AAMR may only be used when sentencing for alcohol-related criminal behaviour and it imposes a total ban on drinking alcohol for up to 120 days. Compliance with the ban is monitored electronically using an alcohol monitoring device which continuously monitors for the consumption of alcohol via an offenders’ sweat.

An AAMR order may be imposed by the court as part of a community order or suspended sentence order where:

• the offence, or associated offence, for which the requirement is being imposed, is alcohol-related;

• the individual is not alcohol dependent or has an Alcohol Treatment Requirement (ATR) recommended or in place; and

• the individual is an adult (18 years or over).

For offenders being released from custody whose offending and risk is alcohol related, an Alcohol Monitoring on Licence (AML) additional licence condition was introduced in Wales in November 2021 and rolled out in England in June 2022. There are two licence conditions available for AML:

• requires total abstinence from alcohol, or

• requires the offender to comply with requirements specified by their Probation Practitioner to address their alcohol needs, this will include restricting alcohol use.

Data sources and methodology

The data in this release are compiled from Electronic Monitoring Services (EMS) contractor data and Alcohol Monitoring Services (AMS) contractor data, which in turn is derived from their case management systems. Caseload information about tagged individuals, as covered in this release, is considered to be of good quality as these data are required to actively manage a case. However, due to the use of different data sources the statistics may differ from other statistics on electronic monitoring requirements (such as those presented within the Offender Management Statistics Quarterly publications which are based on data held by the Probation Service).

This release contains data about:

• Monitored individuals
  A monitored individual is defined as an individual with a device fitted and (if required) a Home Monitoring Unit (HMU) installed. An individual may be subject to multiple RF and GPS orders at the same time. In this instance the cohort an individual is counted under is determined according to the following:

  • if one GPS order (other than GPS bail), choose this;
  • if multiple GPS orders (other than GPS bail), select the order with the longest duration;
  • if multiple non-GPS orders, select the order with the longest duration;
  • if multiple GPS bail orders, select the order with the longest duration.
    

Due to the data being captured in separate systems, individuals with an alcohol monitoring device are counted separately to those with a non-alcohol monitoring device. As with other device types, an individual can have multiple alcohol monitoring orders at the same time. In this instance the individual will be counted once, under the order type with the longest duration. However, there are a few individuals who will be actively monitored under both systems, “dual” tagged, that will be double counted if not accounted for.

• New order notifications
  This is a count of all new order notifications, regardless of whether a device is fitted or whether an individual is already covered by another order.

• Completed order notifications
  This is a count of all completed orders, regardless of whether a device was fitted or whether an individual is still covered by another order.

• Compliance with alcohol monitoring devices
  Compliance with AAMR alcohol monitoring is a cumulative measure, calculated as the total number of days in which the devices have not registered a tamper or alcohol alert divided by the total number of days the devices were fitted. Compliance over the latest quarter is calculated using the data received closest to, but prior to, the start of the quarter, and the data received closest to, but prior to, the end of the quarter. This monitoring data is also used to inform supervision for those with an alcohol monitoring device for licence conditions (AML). Consumption of alcohol may be allowed for some offenders on licence, therefore the compliance methodology used for AAMR reporting does not provide an accurate measure of compliance for this cohort.

Caseload details are received from the contractors at a regular frequency throughout the year. We conduct a range of quality assurance checks on these to identify any errors or inconsistencies in the data. For EMS data, the monthly new starts, and monthly completions files are re-delivered at the end of the following quarter to ensure any errors in previous returns have been corrected and to ensure any late order notifications, which may have been missed from the original extracts, are included. For AMS data, the caseload file is also regularly re-delivered.

As a result of this activity, specific data quality concerns have been identified and adjusted as follows:

Alcohol monitoring: Due to an error in the case management system there is an over recording of the number of individuals with an active alcohol monitoring device fitted. We account for this by using the live system to identify the active devices and matching this to the caseload data.

Dual tagged: Although managed by the same contractor, alcohol monitoring devices are managed through a separate case management system. Some individuals are subject to both alcohol monitoring and electronic monitoring (RF or GPS) and so summing the number of individuals from both systems would be an over-estimate of the number of individuals subject to electronic monitoring. AMS does record whether an individual is subject to an EMS order when a new order notification is received, but this does not provide an accurate count of the number of individuals subject to both device types on any specific date. To estimate the number covered by both EMS and AMS we link those that have a dual tag indicator on AMS and using the EMS reference (where populated), or the name and date of birth, to EMS. Where this join produces a match, and both the EMS and AMS record is a) live at that date, and b) has a device fitted, the individual is considered as being dual tagged.

Processing changes

Since the last publication no processing changes to the methodology have been introduced.

Data limitations

This publication has been produced to the high professional standards as set out in the Code of Practice for Statistics. However, the analysis is only as good as the data upon which it is based and there is inherent uncertainty when the data is derived from diverse administrative data systems.

For example, there are a number of individuals who, according to the case management systems, are covered by a live order but do not have a device fitted. This could be for several reasons, such as the device not yet having been fitted. However, it can also arise from communication issues, such as the correct authority having not been informed when an individual has been recalled to prison.

Furthermore, there are gaps in the evidence base that the administrative system cannot fill. Work is ongoing to address some of these limitations, including:

• Implementation of the EM Data Improvement Plan, which sets out how we will improve data management, quality and accessibility.

• Development of an EM Data Quality Framework, defining how we will manage critical data elements to improve data quality.

• Development of the EM Data Dictionary and Business Glossary, ensuring we capture the data we need and that terms are universally understood.

• Exploiting technology to increase data sharing and provide one version of the truth.

Symbols and conventions

The following symbols have been used throughout this publication.

Symbol	Description
0	nil
-	not available
..	suppressed (see confidentiality section)

Notes

Confidentiality

This statement sets out the arrangements in place for protecting persons’ confidential data when statistics are published or otherwise released into the public domain. The Code of Practice for Statistics states that:

“Organisations should look after people’s information securely and manage data in ways that are consistent with relevant legislation and serve the public good”. (Trustworthiness pillar, T6 Data governance)

To comply with this and with the Data Protection Act of 2018, and to maintain the trust and co-operation of those who use Electronic Monitoring statistics, the following provisions have been put in place.

Private information collected by the Ministry of Justice is stored in line with Ministry of Justice data security policies. Electronic data are held on password-protected networks. All new staff undergo Ministry of Justice security vetting before receiving access to data systems, and all staff undertake mandatory training on information responsibility annually.

Three types of disclosure risk are considered in relation to Electronic Monitoring statistics: general attribution, identification (including self-identification) and residual through combination of sources. Assessment of the risk of disclosure considers the following:

• Level of aggregation (including geographic level) of the data

• Size of the population

• Likelihood of an attempt to identify

• Consequences of disclosure

As a result, the number of monitored individual counts of 2 or fewer are suppressed. This is to prevent the disclosure of individual information.

Publication frequency

This publication is part of the Electronic Monitoring Statistics series. This version of the release will be published quarterly and will be accompanied by a more detailed annual version every July.

New contracts to deliver the Electronic Monitoring service from May 2024 have been awarded. More details can be found here. To ensure the publication series continues to meet our high accuracy and quality standards we may need to temporarily pause the series towards the end of 2024, to allow us to adapt our coding and processes. If there is a pause to the publication series, the full data set will be available when the series restarts. If this will cause difficulties, please do let us know.

Revisions

Figures for the most recent quarter should be treated as provisional, and all other data can generally be considered final. However, we are still embedding improvements to the data processing and as part of the continuous improvement process, minor processing changes may make small changes to the historical figures. Any significant planned or potential future processing changes will be noted in the release prior to their introduction. However, any significant errors will be corrected in line with the Code of Practice for Statistics.

In accordance with Principle 2 of the Code of Practice for Statistics, the Ministry of Justice is required to publish transparent guidance on its policy for revisions. A copy of this statement can be found here.

The three reasons specified for statistics needing to be revised are changes in sources of administrative systems or methodology changes, receipt of subsequent information, and errors in statistical systems and processes. Each of these points, and its specific relevance to the Electronic Monitoring publication, are addressed below:

1. Changes in sources of administrative systems/methodology
The data within this publication comes from a variety of administrative systems. This technical document will clearly present where there have been revisions to data accountable to switches in methodology or administrative systems. In addition, statistics affected within the publication will be appropriately footnoted.

2. Receipt of subsequent information
The nature of any administrative system is that data may be received late. For the purpose of this criminal justice statistics publication, the late data will be reviewed on an annual basis but, unless it is deemed to make significant changes to the statistics released; revisions will only be made as part of the final release containing the calendar year statistics. However, should the review show that the late data has major impact on the statistics then revisions will be released as part of the subsequent publication.

3. Errors in statistical systems and processes
Occasionally errors can occur in statistical processes; procedures are constantly reviewed to minimise this risk. Should a significant error be found, the publication on the website will be updated and an errata slip published documenting the revision.

Contact details

For enquiries, comments or further information, please contact:

HMPPS Electronic Monitoring Performance
Data and Analysis
Ministry of Justice
10th Floor
102 Petty France
London
SW1H 9AJ

Email: ppas_statistics@justice.gov.uk

Alternative formats are available on request from ppas_statistics@justice.gov.uk

Annex A: Glossary of terms

Acquisitive Crimes	Theft, robbery or burglary offences specific to the acquisitive crime pilot
Alcohol Monitoring	A way of remotely monitoring and recording information on an individual’s alcohol consumption, using an electronic device
Alcohol Monitoring Services (AMS)	The organisation responsible for the delivery of Alcohol Monitoring devices, reporting to probation of drinking events and tampers and provision of alcohol monitoring data
Court Bail Order	When an individual is awaiting a court hearing or trial and are released from custody until the hearing or trial but the conditions of their bail must be monitored with an electronic monitoring device
Court Sentence	When community orders or suspended sentence order requirements are imposed on an individual by the court requiring monitoring with an electronic monitoring device
Electronic Monitoring	A way of remotely monitoring and recording information on an individual’s whereabouts, movements and alcohol consumption using an electronic monitoring device
Electronic Monitoring device	May also be referred to as a tag, usually fitted to the individual’s ankle, through which data is collected
Electronic Monitoring Services (EMS)	The electronic monitoring field and service provider
Foreign National Offenders	Offenders who are not UK citizens
Licence	The period in which a prisoner is released from prison to serve the remainder of their sentence in the community
Licence Variation	A change to the conditions in a prison leaver’s licence after they have been released from custody so as better to manage them in the community
Location Monitoring	Satellite enabled (GPS) electronic devices
Order	All requests to the electronic monitoring service provider for a device to be fitted to an individual. Orders can be raised from Courts, Probation, Prisons and Home Office
Immigration Order	Foreign National Offenders released from Prisons or Immigration Detention under ‘Immigration Order Bail’ must be monitored by an electronic monitoring device or non-fitted device (NFD), along with other non-UK citizens subject to deportation proceedings, while awaiting deportation
Post-release Order	When an individual has been released from prison with a licence condition that is monitored with an electronic monitoring device
Specials	Offenders assessed as high or very high risk of serious harm and managed under Level 3 Multi-Agency Public Protection Arrangements (MAPPA) that have been accepted as one or more of the following: CPPC; serious organised crime cases triaged and accepted into the NSD; terrorist risk cases that have been triaged and accepted into the NSD ; those granted bail by the Special Immigration Appeals Commission (SIAC); those made subject to Terrorism Prevention and Investigation Measures (TPIMs); and those convicted for offences under the terrorism act or terrorism act related offences

Annex B: Electronic Monitoring timeline

Overview of Electronic Monitoring policy changes:

Date	Summary
Nov 2018	National rollout of GPS devices begins
Oct 2020	Alcohol monitoring devices launched in Welsh courts
Dec 2020	GPS devices introduced for the immigration cohort
Mar 2021	Alcohol monitoring devices expanded to English courts
Apr 2021	Acquisitive crime cohort launched for eligible prison leavers released on licence in 6 Police Force Areas
Aug 2021	Immigration cohort expanded to non-UK citizens subject to deportation proceedings
Sep 2021	Acquisitive crime cohort expanded to 19 Police Force Areas
Nov 2021	Alcohol monitoring for prison leavers launched in Welsh pathfinder prisons
Jun 2022	Alcohol monitoring for prison leavers expanded to England
Aug 2022	Immigration cohort expanded to Scotland
Aug 2022	Electronic monitoring as Licence Variation pilot launched in 1 probation region
Oct 2022	Acquisitive crime cohort eligibility expanded to offenders who have received a custodial sentence of 90 days or more and been released on licence
Nov 2022	Non-fitted devices introduced for the immigration cohort
Dec 2022	Immigration cohort expanded to Northern Ireland
Mar 2023	Electronic monitoring as Licence Variation pilot expanded from 1 to 5 probation regions
Jul 2023	GPS trail monitoring pilot for Youth Rehabilitation Orders with Intensive Supervision and Surveillance launched in 4 regions
Aug 2023	Launch of Domestic Abuse Perpetrators on Licence (DAPOL) project in 2 probation regions
Dec 2023	Immigration bail pilot to non-FNO persons entering the UK via dangerous and unnecessary routes concludes