Before starting GPS program


The two main technologies in use for monitoring offender’s whereabouts: location tracking (a.k.a. GPS) and proximity sensing (a.k.a. RF)

Theoretically, location tracking is the general case of tracking everywhere including at home.

Proximity sensing enables a supervisor to check whether the offender is near a specific home unit (HU). The hidden assumption here is that by knowing the location of the home unit we can tell the location of the offender, but only when they are in proximity with the HU.

The location tracking technology, can deliver the home detention capabilities but also can report about the offender location even without a proximity to other units, seemingly, everywhere.

It looks like the perfect location tracking and monitoring solution, can make the RF technology unnecessary, but……. we are still far from having a perfect location tracking solution.

Because of that, the selection between the two common technologies is based on many “compromise matrices”. These matrices include axes like what we would like to achieve, vs. offender type, risks, cost and others. As an example, let’s look at a case where we want to enforce an exclusion zone of a neighborhood where the ex-wife of a supervised person is leaving. If this person is organized and can be responsible for charging his device – the location tracking is suitable for him. However, a similar case with a different person who is not well organized and cannot take care of the device charging requirements, may change the decision about the appropriate technology. This unorganized supervised person will probably be under RF technology, confined to his home, in order to protect the potential victim. Part of the implications of this decision are the inability of the supervised to keep working and do essential activities out of home.

In this example, the “compromise matrix” is taking into account the location tracking technology limitation of requiring the supervised cooperation to charge the battery. In other cases, the limited ability to monitor indoor location will be dominant.

Questions we should ask ourselves before deployment of location tracking

  • What do we want to achieve, who are the offenders we want to supervise by location tracking: Controlling prisoner on leave, supervising sex offenders, eliminating offenders associating with each other, domestic violence, etc. Each target may have different implications and needs. E.g. supervising sex offenders may require support of Point Of Interest (POI) exclusion enforcement such as kindergarten and schools. “Prisoners on leave” means strict procedures regarding logistics, maintenance and charging of the equipment in and out of prison, performed by the prison staff and the prisoners.
  • Should we use 1Piece or 2Piece and what are the implications, what is the appropriate offender type for each of these solutions?
  • Who are the users of the system? the probation officers who would like to verify the zones regime is kept, or police officers who would like to use this tool for investigation purposes?
  • Do we align with the appropriate human resources to support location tracking program?
  • Do we align with the appropriate working protocols and profiles?


  • Defining goals and measures (KPI), such as:
    • If the target is to improve the control of a prisoner on leave, compare between solutions of with vs. without location tracking.
    • If the goal is to improve public safety, the control of sex offenders should be compared (what against what? Need at least 2 items for comparison)
    • If rehabilitation via integration with the community is a goal, compare the performance of location tracking vs. home detention
  • Identifying who are the stakeholders (probation officers, police forces, Judges etc.)
  • Writing working protocols – How to define the zones, what is the minimum size, warning zones, handling events, installation procedures (location, process), etc.
  • Organizing the equipment logistics
  • Educating the offender – comparing to the RF technology, the location tracking obliges offender cooperation, by, at least, daily charging of the device
  • Pilot is essential before starting operational program.
  • Location tracking means more supervision resources. The fact that location tracking depends on the offender’s cooperation for charging means more treatment compared to the RF technology, from the operator’s side. Another aspect that causes more complexity is the additional dimension involved: while a violation of home detention refers, usually, to a predefined location which is the offender house or work, the location tracking violation involves the location dimension as part of the equation. Because of that, the normal time that is needed to evaluate RF violation is shorter than in the case of location tracking.
  • Prioritization – Based on violation severity, risk assessment, offenders classification