Challenge to systemic quality failures of GPS tags submitted to Forensic Science Regulator

As the Home Office plans to increase the use of GPS tags for those subject to immigration control, Privacy International has brought a complaint to the Forensic Science Regulator (FSR) regarding systemic failures in relation to the quality and accuracy of data extracted from GPS tags.

Under the Forensic Science Regulator Act 2021, the FSR has statutory powers to uphold standards in forensic science.

Privacy International calls on the FSR to look into quality and accuracy issues related to data extracted from satellite enabled GPS electronic monitoring which risk impeding or prejudicing the course of justice in immigration and criminal proceedings.

Key advocacy points
  • In our complaint to the FSR we call for an investigation into quality and accuracy of the data extracted from satellite enabled GPS tags. This is a form of digital forensics where the extraction of data from satellite navigation is processed and interpreted for use in investigations and criminal prosecutions.
  • Trail data, being the location data collected by the tag and stored by the third-party commercial provider, can be used to consider prosecution for breach of bail conditions and shared with law enforcement agencies.
  • We are concerned there may be systemic failures in relation to the quality and accuracy of data extracted from GPS devices. There are numerous reports of tags failing to charge properly. We have also received reports of the tags malfunctioning in such a way as to suggest that they have been tampered with or damaged, when no such thing has occurred.
  • A further issue of significant concern is the (in)accuracy of the location data produced by the tags. GPS location information may be accurate to a few meters in good conditions, but if the signal from one or more satellites bounces off a tall building, this can give rise to an error of 100m of more.
  • Electronic monitoring via GPS tags is a seismic change in the surveillance and control of migrants in the UK, causing tagged individuals serious feelings of anxiety, social exclusion, and sometimes causing re-traumatisation. Quality and accuracy issues risk prejudicing the course of justice in proceedings and must be addressed.
Light projection on to Lunar House in Croydon

Today, PI filed a complaint with the Forensic Science Regulator (FSR) in relation to quality and accuracy issues in satellite-enabled Global Positioning System (GPS) tags used for Electronic Monitoring of subjects released from immigration detention (GPS tags). We are concerned there may be systemic failures in relation to the quality of data extracted from tags, processed and interpreted for use in investigations and criminal prosecutions. 

The GPS tags are used by the Home Office to collect and process location (trail) data. These tags are procured by the Ministry of Justice who currently have a contract with Capita and a number of other companies for these purposes.

According to the Secretary of State's Immigration Bail Guidance, trail data can be used:

- If a breach of immigration bail conditions has occurred, or intelligence suggests a breach has occurred to consider what action should be taken in response to a breach up to and including prosecution
- To be shared with law enforcement agencies where they make a legitimate and specific request for access to that data
- To assess individuals' representations under their Article 8 right to private and family life

The Home Office can review all trail data when a breach has been notified, for ‘any other indication that criminal activity has taken place’ and share that with Law Enforcement agencies:

“If, during the course of the review of the trail data, by the HO, there is any other indication that criminal activity is or has taken place then the data may be processed and shared with Law Enforcement agencies under Part 3.”

The consequences of breach of bail conditions are severe. Those subject to immigration control can be deprived of their liberty. The Home Secretary has very wide powers of detention that can be exercised without key safeguards such as a time limit or judicial oversight of the decision to detain. Thus, a breach of immigration bail, which could result from a quality issue related to a GPS tag, causing an inaccurate breach notification, could result in an individual being wrongfully detained.

Quality concerns

The recent report by the National Audit Office refers to the use of “obsolescent technology”, “unsupported operating systems, missing system updates and outdated and vulnerable hardware and software.” It notes that maps with location data are “difficult to interpret”. In relation to data quality issues, it points to “poor-quality data – many free text fields lead to a lack of standardisation in data entry, higher likelihood of error and limited opportunities for systematic reporting”.

The Independent Chief Inspector of Borders and Immigration (‘ICIBI’) report March-April 2022 ‘An inspection of the global positioning system (GPS) electronic monitoring of foreign national offenders’ raises concerns stating that:

  • Currently staff rely on Excel spreadsheets they have created themselves and information from Home Office IT systems that they told inspectors they did not trust. There are inconsistencies in data across the Hub’s areas of activity, and no data quality framework is in place to assure that the data is being properly managed, including the sharing of trail data.
  • There was no overall data governance framework in place to provide assurance that data being collated by the Hub met quality standards to assure the consistency and validity of data. This is particularly important where use of multiple spreadsheets introduce an additional risk or error with data entry and processing.
  • Staff consistently said they had not been provided with adequate training for their roles.

In relation to Capita Electronic Monitoring Service, the ICIBI states that:

‘Inspectors requested data held on technical faults and equipment failures. The Home Office stated that although such data was available for the whole contract: “It has not been possible to distinguish between Home Office, acquisitive crime or other cohorts using GPS devices as they all have the same serial number ranges, so it is impossible to tell how many of these were Home Office cases.”

“The Home Office provided estimated data calculating Home Office Immigration Enforcement GPS orders as a percentage of the total GPS orders under the contract. This was then applied to the total faults recorded across the contract. This resulted in the following analysis: “The main reasons for these technical faults were charging issues(81%), SIM [card] (9%) and communication failure (6%) across all cohorts.”

“Instances of faults in December were exceptionally high across the whole of the MOJ contract, with 1,195 devices returned, which included “907 SOLO [EM devices]” which “[Capita EMS] had to recall and return due to a charging fault which all had to go back for repair.”

Battery concerns

We are aware of numerous reports of tags failing to charge properly. Battery depletion can be a breach of bail conditions which can result in civil and criminal penalties including criminal prosecution. A further issue of significant concern is the (in)accuracy of the location data produced by the tags.

The Independent Chief Inspector of Borders and Immigration (ICIBI) reported in his inspection report that there are sixteen different breach types identified by the Home Office. In a six month period, 69.7% had been battery breaches which occurred when a device runs out of charge for any period.

People who are tagged as a condition of their immigration bail are informed that their GPS tagging devices must be charged for an hour a day, and this is echoed in EMS' tagging handbook and handout published on the government's website, and in their (now deleted) YouTube video previously hosted on the HM Prison and Probation Service channel. However, people with tags (including all those who provided case studies, see below) have been informed by the Secretary of State that they should charge the device for at least 2 hours a day, which is at odds with the EMS materials. A handbook on GPS tagging from the Ministry of Justice suggests that fully charging a tag usually takes “at least 2 hours every day”.

Battery life in GPS tags is a recognised problem. This has been noted in the recent reports of the HM Inspectorate of Probation and the Ministry of Justice.

Testimonies given by people who have been tagged reflect that battery life is a persistent issue, and one that affects daily life. We've been informed that when batteries fail, individuals fear being accused of breaching their bail conditions and this significantly affects their mental health. It also restricts their movements, as they need to be close to a charger if the battery dies.

When the battery runs low, the tag will vibrate and the power light will flash red on the tag until it is charged. This can of course happen at any time of the day or night, thereby waking people up in the middle of the night. It may also occur in public spaces, thereby exposing the fact that the individual is wearing a tag. Those with tags report having to rush home quickly to charge their tag while in the middle of other activities, including while caring for children.

"I charge it when I wake up in the morning, I charge it again just before I leave the house to go out for the afternoon, and I charge it again in the evening before going to sleep. Even when I do this however, the tag often beeps when I am out of the house (suggesting that the battery is low), which means that I must charge it immediately".

"The other problem with the tag’s battery problem is that it stops me from sleeping. Every 2-3 nights on average, I will be asleep, and I am woken suddenly because my tag starts vibrating. It is as if I am shocked out of sleep. It seems to be completely random when it happens, it happens even though I charge it before I go to bed every evening".

We've also received numerous reports of GPS tags switching off even when the battery was fully charged. We've been informed that tags can malfunction in such a way as to suggest that they have been tampered with or damaged, when no such thing has occurred.

Accuracy concerns

Accuracy is a noted concern in relation to communications and particularly location data if it is used for prosecutions.

GPS location information may be accurate to a few meters in good conditions. A high-quality position fix requires an open view of the sky. There can be errors in so-called urban canyons, close to buildings and other locations where only a few satellites are visible.

When the satellite signal is particularly weak this can cause a drift, being the movement in the accuracy of the signal. This means that an individual may be recorded some distance from their true location.

The impact of tall buildings relates to the phenomenon often referred to as ‘urban canyons’ where a GPS signal can be disrupted in built up areas where very tall buildings can block the satellites and cause the signal to bounce. If the signal from one or more satellites bounces off a tall building, this can give rise to an error of 100m of more. Larger errors can also arise where the view of the sky is restricted so that only a few satellites are visible. Similarly, much like many smart phones, GPS tags may be less accurate in very rural areas.

To Conclude

The Home Office's GSP monitoring regime raises serious concerns that stem from issues of quality and accuracy of the devices used and the data extracted. As is made clear from the testimonies of those affected, issues with the devices are no small matter. It is quite possible that a faulty battery, or a malfunctioning or poorly fitted device, could result in a person being accused of a breach of conditions, and subjected to criminal proceedings.

We hope that the FSR will take up our complaint and investigate these issues further.