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What Is Electronic Home Monitoring?



Electronic home monitoring, or EHM, is a type of supervision tool used in the criminal justice system, most often by police. The EHM system requires a residential phone line, ankle bracelet, and monitoring device. The residential phone line must have specific features; it cannot have call waiting, call forwarding, or any caller identification functions. EHM systems do not work on cellular phones either.

How Does Electronic Home Monitoring Work?

The EHM monitoring unit obtains a continual coded signal that is transmitted from an ankle bracelet device. The monitoring unit can ascertain if an ankle bracelet is removed by the wearer or has in some way been tampered with, altered, or damaged. The monitoring unit also detects when the wearer enters or exits the home residence.

Many monitoring units today have an accessory to test breath, as well. This accessory is used by law enforcement to ascertain the level of alcohol consumption of the wearer. The telephone line is used to obtain the information transmitted by the ankle bracelet, as well as to receive the information from the monitoring unit. This information is, in turn, sent to the EHM provider via the phone line, as well. The EHM provider is charged with the task of distributing status reports to the appropriate court or probation official monitoring the wearer's case.

What Types of Functions Are Permitted While Wearing an EHM Ankle Bracelet?

Some jurisdictions permit the ankle bracelet wearer to attend and continue with his or her occupation. Some permit the wearer to participate in substance abuse treatment programs and other types of similar programs or functions. This is particularly true if the wearer is a DUI or DWI offender. Court appearances and appointments with legal counsel are also examples of likely permissible excursions for EHM ankle bracelet wearers. Family events and social occasions are usually not permitted.

What Types of Offenses Might Require Wearing an EHM Ankle Bracelet?

  • Probation House Arrest—EHM ankle bracelets are often used for defendants in the criminal justice system under probation house arrest. House arrest is a type of punishment in which the defendant is restricted to remaining in his or her home and is prohibited from leaving for the duration of the punishment, except on approved excursions for work, court, and similar obligations. Under most house arrests, the defendant is not permitted to leave the residence unless he or she has police accompaniment. The perimeter of the residence is used for the defined area for the EHM system. If the wearer ventures outside that perimeter, then the ankle bracelet activates an alarm, and police are notified of the impermissible excursion beyond the boundaries of the residence.
  • Drug Testing—Offenders who commit DUI/DWI offenses may be sentenced to house arrest. Their ankle bracelets often have a blood testing device that monitors their blood, after a slight prick, for the presence of alcohol or drugs. Alternatively, there may be a breath test accessory to monitor alcohol consumption. If the bracelet detects an impermissible level, an alarm sounds for the police.