Electronic monitoring: uses, challenges and successes

Strengths and Weaknesses of EM: A review of the evidence 

EM technologies 

Few studies highlighted technical problems with the equipment.  However,  where there are technical issues, this impacts on effectiveness and the type of monitoring can also affect outcomes. 

While there were a number of case studies identified in which there were no reported issues with EM technologies, technical issues such as lack of signal/coverage, false alarms, and false or missed readings were observed in a number of empirical studies.^[62] Research from Germany found that on average, there were false alarms every three days for each offender on EM.^[63] Research from Spain highlights the failures of GPS monitoring in underground metro systems.^[64]  Other research found that false alerts could be triggered due to the complex technology of EM devices and systems, and their exposure to “a variety of harsh environmental conditions on a daily basis”.^[65]  It should be noted, however, that a number of the empirical studies identified were conducted several years ago, and EM technologies have progressed significantly in recent years. 

A number of monitored people interviewed for research in England reported false breaches, whereby the monitoring company had contacted them to investigate a breach when they had been within their address and complying with their conditions.^[66]  One respondent reported that his motivation to comply was negatively affected by the faults in the equipment, stating: 

“(it) Makes you think that you can go out for a few minutes and blame the equipment…If (the monitoring company) ever asked me why (I was) late, I blamed the equipment”.^[67]  

There was also evidence from Germany of bureaucratic/administrative challenges and issues of inter-agency working;^[68] evidence from England and Wales that suggested the quality of the contractor’s installation and maintenance of equipment impacted on effectiveness;^[69] and evidence from Scotland and the USA on a lack of awareness about how the technology works.^[70] A 2019 evaluation of GPS EM by the Ministry of Justice outlined the challenges of inter-agency working related to communicating the specifics of geographical “away from” conditions and issues resulting from mismatched software between agencies.^[71]

There are differences in outcomes between Radio Frequency (RF) and Global Positioning Systems (GPS)

Some studies from the USA found that GPS EM is more likely to reduce reoffending and non-compliance than RF monitoring.^[72]  Research in Florida found that “those monitored with GPS had a 6% lower failure rate than those on radio‐frequency monitoring”.^[73] However a 2017 systematic review by Belur and colleagues found no statistically significant differences in effectiveness between RF and GPS systems.^[74]

GPS monitoring could be used to develop the evidence base on offending

GPS technology has the capacity to record various types and quantities of information. One researcher has suggested that, over time, the data gathered by the monitoring system could be used to identify patterns of behaviour that pre-empt offending.^[75]

As EM technology has advanced, the amount of biometric and movement data recorded by monitoring systems has increased. The research suggests that information recorded by the monitoring system could be used to plan interventions and improve effectiveness.^[76]  The author uses the example of monitors that detect sleep patterns, based on measurements of Rapid Eye Movement (REM), and the potential for probation officers to use this information to time an intervention based on the monitored person sleeping poorly (an indicator of stress), to check in and provide support.^[77]

Remote Alcohol Monitoring (RAM)

Remote Alcohol Monitoring (RAM) – also known as Transdermal Alcohol Monitoring (TAM or TRAM) or Secure Continuous Remote Alcohol Monitoring (SCRAM) – operates in a similar manner to RF electronic monitoring systems. The technology, in very simple terms, involves the monitored people wearing a bracelet around their ankle that takes routine samples of blood-alcohol levels by measuring the ethanol level of their perspiration. Breathalyser technologies are also used in some instances. The technology has the ability to record whether there are low, medium or high levels of alcohol in a person’s system and thus record their compliance with the conditions of their specific programme. The bracelet tends to be slightly bigger than other EM devices and fit is important to ensure accurate readings and comfort.^[78] RAM systems have been widely available since around 2003. 

Alcohol monitoring differs from other uses of EM because the main aim is to manage or reduce alcohol consumption. In some cases this relates to the criminal justice system however some studies of RAM focus on the use of alcohol from a health perspective rather than in relation to offending behaviour. Studies on RAM in a criminal justice context tend to focus on cohorts of monitored people who have been convicted of drink driving offences, whose offence involved alcohol, and/or who are experiencing alcohol dependence. Comparison between the use of RAM and the general use of EM is therefore problematic. 

A limited number of empirical studies suggest promising results for the use of RAM. 

Research conducted between 2006 and 2008 in North Carolina compared a matched sample of 114 monitored people subject to RAM with a group of 261 unmonitored people.^[79] The study found reoffending rates for any crime were almost 3% less for the monitored group, despite them having a more extensive offending history.^[80] Considering individuals with at least two prior recorded offences, the difference in rates of reoffending was more significant (15.7% of the monitored group reoffended compared to 28.6% of unmonitored individuals).^[81]

In 2014 the Mayor of London Office for Policing and Crime (MOPAC) conducted a process evaluation on the use of the Alcohol Abstinence Monitoring Requirement (AAMR).^[82]  The research assessed the use of AAMR in four areas of London, and used survey data and qualitative interviews of stakeholders, staff and monitored people. The evaluation found that the majority of alcohol monitoring requirements were given as part of a community sentence for an average length of 75 days. The pilot  evidenced a 92% compliance rate with RAM for monitored people on community sentences over 12 months.^[83]  The operational use of AAMR was well understood by practitioners and users, and there was a well-established infrastructure and good levels of inter-agency working, which contributed to the success of the pilot. The option of AAMR was described as “filling a gap in sentencing for alcohol related offences committed by nondependent offenders”.^[84]  The authors acknowledge the limits of the research, but conclude that in general there were a number of positive opinions on and experiences of AAMR.^[85]

Qualitative research from Michigan in 2002 concluded positive reactions from the sample of five practitioners and 19 monitored people in terms of the system’s deterrent value and the freedom it allowed in terms of employment and family life.^[86] A study was conducted in Alaska in 2005 which evidenced a 56% compliance rate with the conditions of the RAM order.^[87]  This study also noted that despite inclement weather conditions, there were no recorded RAM technology failures.^[88] 

Qualitative research from Scotland explored the attitude of 12 offenders serving their sentence in HMP Barlinnie towards RAM.^[89] This cohort were individuals whose current offence involved alcohol and had issues with alcohol misuse more generally. Attitudes towards RAM were generally positive although most of the group recognised that monitoring alone would not change their addictive behaviours and considered it as a mechanism aimed at improving compliance.^[90]  It was also recognised that the RAM tag could not address other factors related to their offending, such as mental health, criminal associates, socioeconomic status, etc.^[91] A number of the group expressed support for RAM as part of an early release scheme, whereby individuals could volunteer to be monitored in exchange for an earlier release date. This type of scheme is supported by literature on incentivising reduced alcohol consumption.^[92]

One of the recommendations of the 2016 Scottish Government Working Group paper was on legislative change, including the introduction of legislation which would enable the use of RAM.^[93]  To date, there have been very few pilots testing the effectiveness of RAM on monitored people released from prison.^[94]

Community supervision and support

In most jurisdictions EM is understood as a tool in a wider network of community support and supervision of monitored people

Scotland is described within the literature as an “outlier” in terms of using EM as a standalone measure.^[95]  In other jurisdictions, including the majority of European jurisdictions,  EM is used as part of a wider package of support and supervision of offenders within the community.^[96] Argentina was one of the only identified jurisdictions that uses EM as an entirely standalone measure.^[97] The legislation in Germany does not allow for EM to be used as a standalone measure and is combined with a programme intended to provide a daily structure to the monitored person.^[98]  In Sweden standalone EM is avoided and is intensively supervised.^[99] The Scottish Government Working Group advised that effective EM use is more likely if used alongside other measures, advising that “where longer term desistance is the ultimate goal, EM should be set within a wider package of support provided by statutory bodies”.^[100] 

In terms of addressing specific offending, EM has been used in other jurisdictions as part of a wider response to an identified social problem. In Northumbria, for example, GPS monitoring was introduced as part of the Multi-Agency Tasking and Coordinating (MATAC) programme for domestic offenders; in London, alcohol monitoring was described as “‘another tool in the box’ of community sentences”;^[101] and in Manitoba, EM was added as an enhancement to the Winnipeg auto theft suppression strategy.^[102] Probation officers in this programme believed EM was “most successful when paired with adequate support”.^[103]  Correspondingly, some of the monitored young people in this programme expressed that the support of the probation officers was essential to their compliance.^[104]

DeMichele emphasised that electronic monitoring should be considered as a tool within a wider network of supports and interventions, using an illustrative case study:

“forms of electronic monitoring are only tools that officers can use. So, asking questions such as “does electronic monitoring work?” are illogical. This would be similar to asking whether computers, cars, or other tools that officers use work. These tools are all dependent on humans and only work as well as the infrastructures supporting them and the people operating them… A prime example involves a California case in which Phillip Garrido and his wife kidnapped and held a young girl captive for nearly 18 years. During part of this time, Mr. Garrido was on parole supervision with GPS tracking, but it went undetected that he had a kidnapped girl (and the two young children he fathered with her) in tents in the backyard. His GPS revealed that he was exactly where he was supposed to be—at his home and in his backyard. Parole officers failed to conduct regular in‐depth searches of the home or even walk through to the backyard.”^[105] 

EM and Reintegration

The relationship between EM and the reintegration of monitored people is complex and is dependent on how reintegration is defined. 

In a Scottish Government review of the use of HDC and open prison, Armstrong and colleagues identified the definition of reintegration as an area for development, noting “the meaning of this should be clearly established to allow for monitoring of effectiveness”^[106] and “(i)t cannot be concluded that HDC…cannot serve integration aims of the penal system, but it does suggest that the meaning of ‘reintegration’ and consequently the services and procedures needed for HDC to support this require some attention and explicit specification”.^[107]  In relation to compliance with the conditions of EM, some literature notes that successful completion of an EM sentence “is not the same as (re)integration – that is, becoming a fully functioning and participating citizen”.^[108]  Graham and McIvor suggest that the “supports and interventions” that address criminogenic needs (i.e. HDC as a means of confining offenders to their house during the evening/night when they are most likely to engage in antisocial behaviour) may be in conflict with measures which support reintegration, such as opportunities for employment, creation of social networks, and development of positive recreational activities.^[109] Research from Belgium^[110] and Scotland^[111] further suggests that where cost effectiveness and reduction of prison populations are the primary objectives, rehabilitation and management of offenders can be side-lined or ignored.

As well as punitive objectives, EM can have the objective of reintegrating offenders in society.   

EM used for the purposes of decarceration in itself may be considered as a form of reintegration based on the logic that being in the community allows offenders to reintegrate better than if they are imprisoned.^[112]  In some literature, HDC is understood as a mechanism to “ease the transition of prisoners from custody to the community”.^[113]  In terms of social capital, the maintenance of social ties is recognised as an important factor for reintegration of offenders.^[114]  Research from Germany found that offenders favoured home detention on EM (as a mechanism for early release) because it allowed them to be with their families sooner and practitioners observed a reintegrative effect of early release on EM, due to offenders being imprisoned for shorter periods and back with their families.^[115]

 

The conditions of release can be used as a means of encouraging reintegration. 

Within the literature EM is identified as a means of enforcing a prosocial lifestyle.^[116]  In the Netherlands, the number of hours a monitored person may be “off curfew” varies between 2 and 17 hours per day depending on probation assessment.^[117] This contrasts with Belgium, for example, where EM is sometimes used as a direct alternative to custody in that monitored people are confined to their house for 24 hours a day.^[118]   A systematic review on EM identified a number of conditions attached to GPS EM in Denmark, Norway, the US, and Australia that encouraged reintegration.^[119]  Aside from requirements related to compliance with movement restrictions, monitored people can also be required to engage in employment, community work, treatment or counselling, maintain a diary of their daily routines, attend or host weekly visits with probation officers, and “avoid contact with criminally inclined associates”.^[120] In Denmark and Norway, being engaged in employment or education is treated as a minimum requirement for offenders to be considered for release on EM.^[121]

EM can provide opportunities for the construction of positive social capital

EM allows individuals to remain in the community, which means family and employment responsibilities are less disrupted than if they were imprisoned. Imprisonment can have the effect of damaging attachments to employment and positive social networks in the community, while remaining in the community allows these connections to be continued and developed.^[123] Williams and Weatherburn highlight that “imprisonment may increase reoffending through other channels”, namely the creation of relationship networks with criminal peers.^[124] Remaining in the community decreases the opportunity for anti-social capital to be built through networks of relationships with other offenders in prison.^[125] 

Research from Scotland^[126] and interviews with monitored people on HDC from New Zealand^[127] and Belgium^[128] show that, although the psychological effects of tagging were challenging for offenders and their families, it was still preferred to the separation imposed by imprisonment. Respondents in Belgium expressed that the associates they mixed with while on EM were not equivalent to the associates they engaged with in prison, and this was of benefit.^[129]  This result was mirrored in a 2001 study from New Zealand, in which for offenders sentenced to EM “the distress of ‘being inside’ motivated them to make good use of their opportunity to stay at home and stay ‘out of trouble’”.^[130] For younger offenders, EM was perceived as an acceptable reason to avoid association with criminal associates, i.e. individuals stated they could not engage in certain high-risk or criminal activities “because of the tag”.^[131] Young people interviewed in research from Winnipeg recalled that many of their friends believed the tag meant the police were nearby and aware of the wearer’s activities, thus they did not want to associate with the monitored person during this period.^[132]

The conditions of EM can affect family responsibilities and relationships.

Research on offender experience from New Zealand^[133] and Belgium^[134] suggests that parenting roles can be maintained as monitored people are not separated from their children, and other family relationships can be improved by spending more time together. Research from Australia^[135] also supports this finding, suggesting both family and community ties can be maintained via EM. Research on recidivism, that examined data of 457 individuals sentenced to EM in France, concluded that EM was most effective for those who were parents.^[136]  The authors conclude this can be explained because “EM is mostly effective for offenders who know what is at stake should they reoffend (most probably incarceration) and do not view EM as a lenient, non-deterrent sanction but as a second chance”.^[137]  Research from Germany concluded that many prisoners applied for post-imprisonment early-release EM so that they could be with their families sooner.^[138]  Interview research with 78 monitored people from England drew similar conclusions.^[139] While the main motivating factor for compliance was the knowledge of their surveillance and that the punishment for failure was imprisonment, respondents also reported that their motivations to comply were directly linked to wishing to remain with their family and maintain employment.^[140]  This research also concluded that monitored people who were housed outside of their community and/or away from their family, or who lived alone, were less likely to comply than those who remained within their established networks.^[141]

Some research provided qualitative examples of how EM restricted offenders from fulfilling family responsibilities. The practicalities of childcare was cited as a factor that increased the likelihood of breaches in research with people on monitored HDC from England^[142] and New Zealand.^[143]  In interview, a monitored person in New Zealand recalled that she had witnessed her daughter fall and injure herself outside of her address within curfew hours. She had remained within the address, contacted the monitoring company and they had allowed her to tend to her daughter without recording the breach, however the incident had caused her great distress.^[144] Recalling his experience of being tagged, Kilgore discusses his experience when his 96 year old mother called him around 2am to alert him that she believed she was having a heart attack.^[145] Rather than attend straight away, Kilgore contacted the monitoring company and was advised that to temporarily amend the restrictions, his parole officer would have to assess the situation. As the incident occurred out-of-hours, the parole officer did not contact him until the following day and he was unable to attend hospital with his mother.^[146]

Some research found that EM can negatively impact upon a monitored person’s family, particularly those who reside with the person on EM.^[147] The 2017 G4S statistical bulletin included feedback from a monitored person, who stated “my partner felt like she was also on a tag”.^[148] Amongst co-residents of monitored people, the Scottish Government Working Group found evidence of anxiety, guilt and stress related to the perception they were responsible for ensuring the monitored person’s compliance with EM conditions and inclusion in social events.^[149] In response to this concern, the Working Group recommended additional information and support be made available for the families and co-habitants of electronically monitored people.^[150]  Some of the literature describes a monitored person’s familial support as fundamental to their compliance with the conditions of EM.^[151]  The interim guidance on RLO risk assessment also recognises that:

"(t)he most important element is the need to investigate what the likely impact of an RLO would be on the household where the person is to be restricted to. It is very important that those living with the person understand what an RLO involves and that they are prepared to co-operate and support the person if an Order is made”.^[152]  

It should be noted that a monitored person’s release to an address on HDC relies on the continued consent of the householder responsible for the property. If consent is withdrawn and no suitable alternative is identified, the individual will be returned to prison. This was identified as a challenge in some of the literature. To prevent householders withdrawing consent, Probation officers in Gwent, Wales revised their process of liaising with the family of monitored people to provide more information and improve engagement.^[153]

The flexible use of EM can be used to incentivise reintegration. 

EM can be can be flexibly applied dependent on offence, offender demographic, and the conditions necessary for release.^[154] McIvor and Graham’s (2016) Scottish review recommended using EM as an incentive for reintegration, and suggested it is currently under-utilised with standardised curfews most common. In the Netherlands, the number of hours an offender may be “off curfew” varies between 2 and 17 hours per day depending on their daytime activities.^[155]  Probation officers can amend orders to allow monitored people to leave the house for more hours per day if it is for employment, training or education; or, if individuals are compliant over time, curfews can be amended to allow for more hours away from the address as an incentive. A study of monitored people’s experience on HDC in New Zealand recorded that a single mother had expressed how important it was for her to accompany her children to school. This had been negotiated with the parole board and her curfew amended accordingly.^[156] Applied in this way, EM ‘may foster reintegration back into society’.^[157] There is further supportive evidence of the benefits of flexible EM use from the Netherlands^[158] and reviews of international evidence.^[159]  In Scotland, the majority of curfew restrictions are imposed for the standard period of 7pm to 7am, although guidelines allow for this to be adapted to suit the individual as necessary.^[160]

EM can provide structure for the monitored person 

An offender may be provided structure in terms of their days being more strictly timetabled, the increased responsibilities associated with wearing a tag, maintaining regular sleeping patterns, and reduced opportunity to associate with criminal friends.^[161] Research also suggests that monitored people have an increased sense of motivation to comply while on tag.^[162] Auto-ethnographic research (i.e. the researcher wears a tag) from Australia^[163] and England^[164] evidenced that wearing the EM device on one’s body served as a physical reminder to comply with the conditions of its use. Further, it forced the wearer to make plans for their day ahead (such as which routes to travel and the advance scheduling of appointments) in order to comply with conditions. The three researchers separately concluded that, although being subject to an EM tag was psychologically and physically burdensome, the punitive impact of wearing a device lessened over time.^[165] Monitored people in the alcohol monitoring pilot conducted in London also had concerns about the ‘wearability’ of the tag, in terms of comfort and its bulky size.^[166] Monitored people interviewed in research from Belgium noted that the conditions of the tag forced them to be far more aware of time.^[167] 

EM can increase the likelihood of a monitored person gaining or maintaining employment.

Research from Denmark^[168] examined the impact of EM compared to imprisonment on social welfare dependence (which is described in the paper as synonymous with unemployment). The study found that monitored people decreased their social welfare dependence by an extra 15 to 30 days within the first year after release, though this trend only applied for those under 25, there was no effect on older offenders. Studies from Sweden^[169] and the Netherlands^[170] also found EM enabled monitored people to maintain employment, mainly due to remaining in the community but also because EM conditions could be amended to accommodate their hours of employment. In terms of EM’s effectiveness, research from France evidenced recidivism reduced by 9% for EM offenders whose sentence conditions obliged them to engage in employment.^[171]

EM can decrease probation officers’ face-to-face contact with people serving community sentences

Qualitative interviews with probation officers in Winnipeg, Canada suggested that GPS EM worked to reduce the amount of time spent in direct contact with a monitored person.^[172]  Prior to the use of GPS EM, officers tended to have daily contact with their clients, either face-to-face or by phone. Following the introduction of EM, some probation officers felt that, rather than make contact with an individual, staff were checking the person’s whereabouts using the GPS mapping system.^[173]  Some of the staff felt that the level of human contact required by the supervision programme was sufficient and GPS EM was an unnecessary and ineffective addition.^[174]

Dependent on home circumstances, EM may not contribute to reintegration as intended.

Some of the literature highlights that a monitored person’s home circumstances and community network may affect their reintegration. If an individual’s conditions of release confine them to a place, it might mean they cannot avoid criminal associates attending their address, and the likelihood of breaching could be increased. In research from England, qualitative interviews with monitored people suggested that some breaches of curfew resulted from monitored people being targeted with threats and harassment while on curfew in their home.^[175]  Some of those interviewed described how they felt like “sitting ducks” because their exact whereabouts were known.^[176]  This resulted in a number of them choosing not to answer the door during curfew hours, which is when many monitoring checks are conducted and their failure to appear would result in a recorded breach.^[177] James Kilgore is an academic who spent 6 and a half years in prison in the US and wrote about his experience on electronic monitoring. On being released, Kilgore stated “(i)f you want people to avoid getting re-involved in criminal activity, you have to give them the opportunity to change their life, not keep them chained to their living room.”^[178]  Kilgore suggested that for some offenders a move away from the community is beneficial.^[179]  

EM can have a negative impact on securing and/or maintaining employment. 

By contrast to research that suggested release on EM allowed monitored people to secure or maintain their employment, some of the literature suggested EM can damage employment opportunities. The stigma of wearing a tag – particularly as it is negatively portrayed in the media – is perceived by some to reduce their ability to secure or maintain employment while tagged.^[180]  Anecdotal evidence of monitored people losing their job after informing their employer of their EM conditions^[181] or finding it difficult to work because of the tag^[182] are provided in the literature.

The impact of EM on reoffending 

When considering research on reoffending, there may be differences between people released on EM and those released following a prison sentence. 

It should be noted that research design is of particular importance in assessing the effectiveness of EM. In some studies on reoffending, people sentenced to EM are compared with a matched sample in prison. There are a number of important differences between offenders released on EM and those released following a prison sentence. First, while both groups may have an equal opportunity to reoffend, there is a higher level of deterrence for those monitored by EM, first because detection is considered more likely while monitored and second because reoffending is a breach of EM conditions which is likely to result in revocation and imprisonment.^[183]  In addition, a process of risk assessment is used by the judiciary, prison and probation authorities to evaluate the risk of reoffending posed by an offender and in most cases it is only lower risk offenders who are released into the community.^[184] On this difference, Di Tella and Schargrodsky contend that “low post release recidivism of a group of offenders treated with electronic monitoring could simply reflect the success of the legal system at the selection stage.”^[185]  Other factors such as the individual’s level of remorse will also influence the decision for them to be released on EM.^[186] Taken together, a lower risk of reoffending and higher level of remorse may mean in practice that monitored people are, in general, already at a lower risk of reoffending,^[187] particularly when compared to those released from prison who were not deemed eligible for EM. Comparisons between groups of monitored and unmonitored people on community sentences can be difficult for similar reasons.^[188] 

There are mixed but promising results regarding reoffending, reconviction and failure/breach rates. 

A literature review found that there are a number of studies which evidence reduced reoffending on EM, a number that have produced inconclusive findings, and a number that concluded that EM has no significant impact on reoffending.^[189]  

Ministry of Justice research from 2011 concluded that monitored people released on HDC were no more likely to reoffend than those in a matched sample who were not eligible for release.^[190]  In a review on RAM this finding is reinforced by the authors who write “(e)lectronic monitoring is as effective as incarceration, and less expensive”.^[191]  

A separate meta-analysis of 17 studies, which examined quantitative data on reoffending, also concluded that “EM of offenders does not have a statistically significant effect on reducing re-offending”.^[192]  This research did highlight, however, that three of the studies examined evidenced reductions in reoffending when compared to the alternative of imprisonment. Research from New South Wales, Australia found that, conditional on reoffending, there was very little difference in the likelihood of committing serious crime for monitored people compared to those who served their sentence in prison.^[193]

In Australia, Argentina, the US and elsewhere in Europe research has evidenced that EM reduces reoffending. Research of 16,475 cases from Sydney, Australia compared individuals released on EM with those released after prison over 24 months.^[194]  The research found monitored people serving their sentence on EM were associated with a 25% reduction in reoffending compared to the prison sample.^[195] In Sweden, research compared 260 electronically monitored people as part of an early release with a control group who served the full term of their prison sentence.^[196]   Over three years, reoffending rates amongst the early release cohort were significantly lower than in the comparison group. In Spain, research in 2001 followed 53 individuals released from prison on EM (compared with a random sample of 307 individuals sentenced at the same time who remained imprisoned and 251 others released without EM). The reoffending rate of the EM group was 0%, compared to 9% of those on community sentences and just under 38% of the imprisoned group.^[197]

A study of 2,827 offenders in France, of whom 457 were sentenced to EM as an alternative to custody, found a 9–11% reduction in reoffending after 5 years compared to a matched comparison group who were imprisoned.^[198] This research suggested that EM reduced the probability of being imprisoned after 5 years by 18%, compared to a matched prison population.^[199] In this group, reoffending was least likely among electronically monitored people “who received control visits at home from correctional officers, were obliged to work while under EM, and had already experienced prison before”.^[200]  

Evidence from the US and Denmark shows that EM can reduce breach/failure rates. Bales et al. (2010) conducted the largest comparative analysis of 270,000 monitored people on RF EM in Florida and concluded that, compared to unmonitored individuals on community supervision, RF EM reduced failure rates by approximately 30%.^[201]  Breach rates decreased by a further 6% in cases where GPS EM was used. The same research (comparing 5034 electronically monitored people to data on 266,991 individuals not placed on EM) found that, over a period of 6 years, monitored people were 31% less likely to breach the conditions of their sentence than comparable groups not on electronic supervision.^[202]  In terms of breach rates, research from England and Wales that examined 217 files of individuals sentenced to EM found that only two had no breaches recorded and over half had over 50 breaches recorded on file.^[203]  Most of the breaches were minor violations, the majority relating to time violations (i.e. being away from the curfew address within curfew hours) and the majority were not recorded as formal breaches.^[204]

Research from Indiana, USA, studied 293 monitored people released on EM home detention, comparing those who successfully completed the programme and those who did not, i.e. who breached conditions, were re-arrested and/or imprisoned.^[205]  112 people successfully completed the programme and in contrast to other studies it was concluded that those who completed the programme were more likely to reoffend than those who did not complete.^[206] The authors note the limitations of research design, including that reducing reoffending was only one aim of the programme, and successes were concluded in other evaluation outcomes.^[207] 

Much of the research focuses on GPS (rather than RF) and emphasises that EM must be monitored and supported in the community for a reduction in reoffending.^[208]  There are also differences in outcomes for different demographics of monitored people. Research from New South Wales, Australia associated reduced rates of reoffending with individuals aged under 30 and for those who had not been imprisoned before.^[209]  This research evidenced that the benefit of EM, in terms of reducing reoffending, persisted for 8 years for younger offenders compared to a matched sample serving their sentence in prison.^[210] It is important to note that the system in New South Wales provides monitored people with “tailored rehabilitation programmes along with intense supervision” and this may further explain improved outcomes.^[211]

GPS EM can increase the compliance and reduce reoffending rates of sex offenders. 

In an empirical study of 270,000 people with convictions in Florida, Bales et al. (2010) found that sex offenders were the most compliant cohort on EM. Data from New Jersey on 225 sex offenders monitored over 3 years found that those on GPS EM were significantly less likely to commit sexual offences than the US average on sex offenders released from prison (0.04% reoffended compared to the national average of 5.3%).^[212]  In a study of 516 sex offenders in California, Gies and colleagues evidenced similar empirical findings, concluding that, compared to a matched group on non-monitored parole, those on GPS EM had significantly higher rates of compliance and lower rates of reoffending.^[213]  In this sample, breaches were almost three times as likely for those on traditional parole compared to those on EM.^[214] 

Evidence suggests community supervision can reduce reoffending of offenders managed by EM.  

Research on the use of EM for sex offenders from New Jersey found reduced reoffending of electronically monitored people, and this was in part explained by the ‘containment approach’ adopted by the federal authorities, which involved “intensive parole supervision, offender-specific treatment and polygraph examinations” which resulted in offenders perceiving that their movements were constantly observed and thus encouraged compliance.^[215]  

Research from France offered similar conclusions - compared to individuals serving prison sentences, EM reduced reoffending, and was further reduced for those who were visited at least once by supervising staff during their curfew hours.^[216] In terms of reoffending, EM was also found to be more effective for individuals who were supervised for longer (above the median period of 2 months).^[217] The authors suggest that the “difference in outcomes suggests that control visits act as a strong deterrent” and highlight that this correlates with qualitative research conducted with offenders in England.^[218]  The research from England examined information from case files on 217 individuals sentenced to standalone curfew orders and interviews with 78 of those monitored.^[219]  The study evidenced a positive correlation with compliance for monitored people who had a good relationship with monitoring agency staff or probation officers.^[220]

If a monitored person commits a crime, GPS EM can improve the process of evidence-gathering.

GPS EM has the capacity to monitor an individual’s whereabouts at all times. As technology has developed, it is possible to overlay data on the monitored person’s movements with data on crime loci and incidents, to identify correlations or to eliminate an individual from a criminal investigation.^[221]  Additionally, in the event of a crime, a monitored person’s location data can be used to identify other potential sources of evidence such as CCTV and eye witnesses.^[222]

The effectiveness of EM is undermined if there are delays in responses to breaches. 

Some research has found that delays in responses to failures, due to technological issues or slow responses by monitoring agencies, can negatively impact upon EM’s deterrent effect for monitored people.^[223]

The cost of EM

Based on research, the cost of HDC is less than imprisonment.^[224]

Scottish Government research conducted in 2009/10 found the weekly cost of imprisonment was £610 compared to £126 per week for a person managed on HDC.^[225]  In 2013, the average cost per EM order per day in Scotland was estimated at £10.17 (approximately £3712 per year). The average cost per prisoner place for a year was £37,059.^[226] Taking into account the costs of HDC/release assessment and preparation, there is still a cost saving, particularly over longer periods: the cost of assessment/preparation was estimated at £602 per prisoner, and the weekly cost of imprisonment was £610. This equates to a saving of £1234 over a 4 week period and £10,914 over a period of 24 weeks HDC.^[227]

On cost, Professor Mike Nellis suggests that a presumption towards release on EM is defensible particularly if the saving is used to support monitored people in the community^[228]. In a separate publication, Nellis notes that once monitoring centres and practices are established, the cost of upscaling HDC (in terms of thousands monitored increased to tens of thousands) is relatively low.^[229]

There is evidence from other jurisdictions that supports the cost benefit of EM. 

Research from England in 2016 found that, over 90 days, the cost of monitoring a prisoner in custody was £6500 compared to £1300 for an individual released on HDC over the same period.^[230]  Research from Spain calculates that the cost of one meal in Spanish prisons costs more than an electronic monitoring bracelet does per day.^[231]  Based on average length of sentence and number of court appearances, research from New South Wales, Australia estimated the average cost saving per person diverted to EM instead of being imprisoned was $25,200.^[232]  Controlling for the cost of staff time (though not overtime), equipment and administrative overheads, empirical research by the US National Institute of Justice in 2007 found that the median cost of managing an individual using GPS was $5475 and the median cost of incarceration was $30,000.^[233] In California between 2008-9 EM was estimated to cost $36.00 per day per parolee, while imprisonment was estimated at $129.00 per day.^[234]  In Florida EM is used as a condition of bond for a person’s release from prison and in 2010, the use of EM freed 19,680 man/days from Seminole county jail, saving the state in excess of $1.7 million per annum.^[235]

An additional cost saving was identified in the Seminole County study, related to accused person’s appearance at court. The research found less than 1% of offenders failed to appear at court, concluding that “(t)hey know that they are being watched 24/7, and that they will be found very quickly if they do not keep scheduled court appearances”.^[236]

EM’s cost effectiveness is conditional on a number of factors 

The available literature highlights that some of the cost savings are conditional on the presence of a number of factors. It is suggested, for example, that GPS EM is more costly than RF.^[237] One researcher highlights that, in the case of GPS monitoring, the more data that is collected, the larger the resources required to sort and analyse the data set.^[238]

Research from Scotland found that surveillance and immediate response obligations can keep costs up.^[239]  A separate Scottish Government research publication concluded that costs are only reduced if “the sentences they replaced were relatively long”.^[240] The same study found that EM pre-trial bail is more expensive than custodial remand in Scotland.^[241] Further evidence from California on sex offenders evidenced increased cost of EM monitoring (in comparison to other forms of community monitoring).^[242]  The literature highlights that staff time and resources should also be considered. A parole agent with a GPS caseload can take a considerable amount of time, with estimates of 40% of an officer’s workday being taken up with a standard caseload of 25 parolees.^[243] 

There is a limited evidence base on the cost incurred by the whole system operational cost of EM. 

The literature notes that assessing the whole system cost of EM is difficult because there are a number of different criminal justice agencies involved in a monitored person’s management, all with separate budgets and patterns of collaborative working.^[244] 

Additional costs, associated with investigating failures, lost connections, or false alerts of GPS technologies and staff overtime for EM, and construction of new prison property for those incarcerated, are not considered in the available research.^[245]  Research from Spain, for example, found that for a BEM project aimed at monitoring perpetrators of domestic abuse, each system unit – for the offender and victim - costs €600.^[246]  It should also be noted that in some states of the US, monitored people are obliged to pay the daily cost of their monitoring equipment, which would be covered by the state in other jurisdictions, and this therefore impacts on cost calculations. 

The 2019 Ministry of Justice evaluation of GPS monitoring highlighted the need to establish a robust infrastructure to support the introduction of GPS EM, and this required time and resources.^[247] Respondents in the evaluation also highlighted the perceived additional costs in terms of court time and administration.^[248]  In particular, the time required for decision-making processes associated with GPS EM were prohibitive for courts setting bail conditions. One respondent reported:

“The courts are saying, ‘We want to deal with this today, I'm not giving you another 15 minutes to sort a map out.' They'll just say, 'It doesn't matter, we'll go for a restraining order instead.'” ^[249]

In terms of cost effectiveness for Scotland, little is documented regarding the cost of EM breaches. To fully evaluate cost savings, further data on the rates and costs of breaches would be required.

The ethical considerations of EM

Up-tariffing and net-widening are a risk 

EM can allow net widening or penological drift, whereby offenders who would not be sanctioned otherwise are monitored by EM. Evidence from international reviews^[250] and from research conducted in specific locations, such as Scotland^[251]; Belgium^[252]; Germany^[253]; and the USA^[254] highlighted this issue, particularly when EM is used as an alternative to pre-trial remand.^[255]  Net-widening may also result in an increase in breach rates due to more stringently monitored conditions.^[256]

In research from Winnipeg, probation officers found that GPS EM meant practitioners had no discretion with regard to non-compliance and minor violations, even in instances where there was no intent to commit crime (such as being late for curfew), must be recorded as an offence.^[257]  Some of the young people in the Winnipeg programme cut their tag off and were charged with theft (of the monitoring device and phone) and mischief, despite otherwise complying with the conditions of their release.^[258]  Correspondingly, some of the young people felt that the tag was setting them up for failure due to the rigid conditions and lack of leeway regarding non-compliance.^[259]  One respondent also reported that he perceived his probation officer was more “harsh” when he was electronically monitored and felt that the message of the programme was “one mess up equals gone”.^[260]

In addition, literature on the monitoring of sex offenders highlights that for some monitored sex offenders, the conditions imposed by EM may be disproportionate because a subset of this group are very unlikely to offend again.^[261]

EM can cause stigma, distress and shame for the monitored person  

There are a number of debates within the theoretical literature comparing the use of EM as surveillance with its use for confinement and how this impacts upon an individual’s psychological wellbeing.^[262]  The literature on EM highlights that GPS monitoring systems in particular can infringe upon on an individual’s privacy.^[263] 

The physical act and visibility of wearing an electronic tag may have distressing effects on a monitored person.^[264] This can relate to a monitored person’s need to disclose to friends and family why they cannot leave the house; perceiving that friends and family know their every move; and the embarrassment associated with wearing a physical and visible tag or carry a monitoring box on their person at all times.^[265]  Qualitative research of monitored people in Pennsylvania and Winnipeg found that some monitored people experiences shame and embarrassment and this was exacerbated by having to explain why they were wearing the tag to friends and family.^[266]  Kilgore, the American academic who had served time in prison and on EM, highlighted that the inflexible application of EM meant accidental breaches, due to a late bus or flat tyre during one’s commute, meant the reality of living with a tag could be very stressful.^[267]  Other research respondents – particularly females – reported they felt they had to be mindful of what clothes they wore to ensure the tag was hidden.^[268]

Other monitored people highlighted the strain EM caused on their relationship with their family. Monitored people reported that the sharing of domestic responsibilities was sometimes curbed by EM and caused conflict.^[269] Tensions within intimate partnerships have also been reported across a number of studies.^[270] Respondents in research from Belgium discussed how EM could make them feel powerless as they were unable to participate in family life as normal.^[271]  One respondent recalled how their children took advantage of the curfew, staying out late with their friends knowing that their parents could not venture out the house.^[272]

Survey data of monitored people found that almost a third would prefer one month in jail compared to 6 months on EM and the authors attributed this finding to the shame and embarrassment associated with wearing a tag.^[273] Overall however, research which focuses on offender experience concludes that offenders still prefer to serve a sentence of EM than to be imprisoned.^[274] 

EM is not always appropriate for people with additional vulnerabilities. 

EM is not considered appropriate for offenders with mental health issues or severe substance addictions^[275]. The recent Ministry of Justice GPS pilot excluded those who were assessed to have “‘serious identified mental health or learning disabilities” from consideration from GPS EM.^[276]  Evidence from Norway evidenced higher reoffending rates for offenders of drug-related crimes.^[277]   In the Netherlands “EM is less likely to be imposed where people have serious substance addictions, serious mental illness and/or strongly impaired intellectual capabilities”.^[278] Ministry of Justice research also identified challenges of monitoring people with “mental health conditions, learning disabilities and chaotic lifestyle” who may have been incorrectly assessed as eligible^[279] for EM.

EM can negatively impact minority groups.

Some of the available literature, particularly from the USA, highlights the disproportionate use of EM on minority ethnic populations.^[280] Kilgore discusses the net widening surveillance of certain groups, namely black and Hispanic communities and school truants in the US, and Buchanan contends that GPS EM can heighten offenders’ senses of powerlessness.^[281]  

EM can negatively impact people living in poverty

In the US, many offenders are obligated to pay the cost of their monitoring equipment and this necessarily excludes those from lower socioeconomic groups from being released on EM.^[282] In interview, a monitored person in Belgium recalled that they lived alone and had very few resources, no television, at times no food and had very few prospects of employment.^[283]  As a result, the monitored person intentionally relinquished their release on EM to return to prison. In the Winnipeg auto theft suppression strategy, the young people were issued with mobile phones as part of the GPS monitoring programme. If the phone was lost or the police were unable to locate it, the young person was charged with theft and required to repay the cost of the device. One of the probation officers interviewed in research emphasised that this would be a debilitative cost for many of those involved in the programme because of their socioeconomic status.^[285]

Offenders on EM bail can be disadvantaged

According to the 2007 Scottish EM bail pilot – offenders on EM bail were given longer custodial sentences (121 days versus 93 days for the comparison group) and longer bail periods^[286]. It should be noted that backdating of custodial sentences was not possible when this pilot was set up, and this also affects cost.^[287]

EM is not fully standardised

The Scottish reviews by Graham and McIvor found differences in how EM orders and breach thresholds are managed and imposed.^[288]  There were also differences in how breaches were monitored and reported. It was identified that some “special sheriffs” agree specific arrangements with G4S for breach proceedings as part of a problem-solving court approach.^[289]  

Evidence from Argentina and New Zealand highlighted the different propensities of judges to utilise EM as a sentencing option.^[290]  Efforts were made in these studies to control for the differences in judicial decision-making, which were significant.^[291]

Negative incidents related to EM can be scandalised by the media and there is poor public understanding of its use. 

Evidence from Scotland, Germany, the USA and a systematic review suggests that there is a poor public understanding of EM and there is the potential for negative incidents to be disproportionately criticised and/or scandalised by the media, with a lack of positive reports of EM.^[292]

Nellis has documented the negative and sometimes sensationalist media response to EM in a number of his publications.^[293] In general the British press has reacted negatively to the use of EM for individuals serving community sentences.^[294] In Winnipeg, the GPS EM pilot for young offenders convicted of theft of motor vehicles received attention from the press, which was mainly negative and which politicised the use of EM and blurred the distinction between GPS and EM in its reporting.^[295]