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Use of Location Monitoring in the Field

Recommendation of Location Monitoring

When supervision of a person involves LM, procedural guidance endorsed by the Criminal Law Committee provides that the officer recommends the most cost-effective and least restrictive, yet appropriate, LM equipment option available to the person under supervision. The level of restriction and type of equipment chosen should always depend on the risk level of the person under supervision; the higher the risk level, the greater the need for more restrictive LM equipment. The risk and needs of a participant on LM should constantly be reevaluated by officers to determine if the court should modify the type of equipment or the component. Effective management will avoid the risk of under-supervising higher risk participants and over-supervising lower risk participants. 

LM during pretrial release will likely be combined with pretrial services supervision and will usually be ordered for persons with identified issues such as failing to appear, sexual deviance, weapons possession, and violence. A location restriction condition should be recommended or selected if an individual charged with an offense poses such a risk that the individual’s presence in the approved home or their location in the community needs to be verified through LM equipment. For all offenses involving a minor child, as listed at 18 U.S.C. § 3142, the Adam Walsh Act requires that the court impose LM and must impose a condition requiring the defendant to comply at least with at least a specified curfew (18 U.S.C. § 3142(c)(1)(B)(vii)). The imposition of this condition must be satisfied by using RF or GPS equipment. Although voice recognition and virtual monitoring supervision are LM technologies, they are considered a low-risk alternative that does not provide continuous monitoring and should not be used for this high-risk population.

Individuals with lower risk levels and lower needs who are enrolled in the Federal Location Monitoring (FLM) program during prerelease custody are, to the extent practicable, to be placed on home confinement (i.e., home detention) for the maximum amount of time permitted under 18 U.S.C. § 3624(c)(2). The use of RF equipment is recommended for FLM participants; however, as with any LM participant, the type of LM equipment may be modified given the risk level, personal needs, and circumstances of the individual on LM with management approval. 

During post-conviction supervision, LM equipment allows an officer to know when a person under supervision is in or out of the approved residence, enabling the officer to schedule community contact visits. Use of GPS equipment allows officers to detect noncompliance, such as going into prohibited areas (e.g., parks, childcare, or near third parties protected by a court order). As with any individual subject to an LM condition, the type of LM equipment used will be based on the individual’s risk level.

The use of LM technology can be recommended as a sanction or action when addressing violations, but it should be recommended only to address specific risks associated with a violation. Again, the type of LM equipment and component used will be based on the individual’s risk level.

In general, use of voice recognition, virtual monitoring, or RF equipment is best suited for participants with lower risk and need levels, while GPS equipment is the preferred supervision tool for higher risk individuals in need of enhanced supervision.

Location Monitoring Summary Chart

Type of Equipment

Operational Mechanics Potential Limitation(s) When Best to Impose*

RF Landline

A non-removable, waterproof, and shock-resistant transmitter is affixed to the wrist or ankle of a participant 24 hours a day. The ankle is the preferred location, and the wrist should be an option only for verified medical reason. The transmitter sends a constant radio signal back to a receiver in the participant’s residence. The transmitter reports only when a participant enters or leaves the equipment’s detectable range.

The officer is automatically notified when equipment is tampered with when in range of the receiver or when the participant enters/leaves a specific location (residence). 

Location data is only available for the location where the receiver is placed (residence) and does not report where or how far the person under supervision has gone if the participant leaves the receiver’s range.

Violations cannot be detected when the participant is out of range of the receiver.

Monitoring lower risk individuals.

May also be used for individuals sentenced under the Adam Walsh Act and on a curfew.

Recommended for individuals enrolled in the FLM program during prerelease custody.

RF Cellular

Same as RF-landline except that it transmits data via cellular signal and not a telephone landline.

Same as RF-landline except possible cellular service issues if the participant lives in or travels to a remote or mountainous area. Same as RF landline


A non-removable, waterproof, and shock-resistant GPS tracker is affixed to the ankle of a participant 24 hours a day. The participant is required to charge the GPS tracker at least daily or as directed. The participant’s location is detected by GPS satellites, cellular towers, and/or Wi-Fi.  GPS trackers receive satellite signals; they do not transmitter, nor do they require an unobstructed view of the sky.  GPS operations depend on an accurate time reference, which is provided by atomic clocks.  Each GPS satellite transmits data that indicates its location and current time.

This system involves close monitoring of the data by the supervising officer and can be labor intensive for officers (monitoring participant’s movements 24/7).

Participant required to charge their GPS tracker daily or as directed.

Possible cellular/GPS service issues if the participant lives in or travels to a remote or mountainous area. 

When enhanced supervision is needed and the whereabouts of the person under supervision must be monitored when the participant leaves the approved residence, or when a third-party risk has been identified.

May also be used for individuals sentenced under the Adam Walsh Act and on a curfew, but GPS should not be the default technology for these cases and an individualized assessment should be done.
Voice Recognition (VR) Automated system places telephone calls (random or scheduled) to verify a participant’s presence at a location (e.g., residence, employment).

Requires a telephone landline.

Officers are expected to investigate any violations within one business day, but a violation does not require an immediate response.

Best suited for monitoring lower risk, non-violent persons, because VR technology does not provide continuous monitoring. 

May be used for participants who have medical/physical conditions prohibiting the use of traditional LM equipment.

Virtual Monitoring Supervision

An application (app) is downloaded to the participant’s mobile device.  A participant receives a push notification (random or scheduled) to their mobile device directing them to complete a “check-in” contact using two-factor authentication (e.g., facial recognition, fingerprint, and/or password), which uses the mobile device’s GPS location services to report their current location or verify they are within a zone (e.g., residence).

This technology is not included within the national contract and requires procurement of a non-competitive contract by an individual district. 

Requires a mobile device (e.g., smartphone, tablet).

Data plan preferred.

If the participant is out of cellular and/or Wi-Fi coverage during a required “check-in”, the pending data is submitted when coverage becomes available. 

Monitoring lower risk individuals.

May be used for participants who have medical/physical conditions prohibiting the use of traditional LM equipment.

* The most cost-effective and least invasive, yet appropriate, LM equipment option available to the person under supervision should always be recommended, and the risk and needs of a participant should constantly be reevaluated by officers to determine if the court should modify the type of equipment and the component.

Sample Condition Language for Court Orders

The following language may provide guidance when imposing a LM condition. While this section includes sample language that is intended to be clear and legally sound, there may be cases where the court or the parties determine that different language is necessary to account for the individual circumstances in that case. There may also be case law in individual circuits requiring variations from the sample language. For instance, circuits vary in the level of specificity required in conditions to prevent over-delegation of authority to officers. Each district should fashion LM condition language in a way that comports with circuit case law requirements.

To help maintain manageable LM caseload sizes, the AO provides caseload size guidelines for courts to consider. The AO, however, also recognizes that each office will ultimately have to make its own decision as to what caseload size is appropriate based on the circumstances of the office and nature of the case. 

Pretrial Release

Sample language for imposition of a condition of LM is available in AO Form 199B (“Additional Conditions of Release”). 

Post-Conviction Supervision

The following is sample language the court may use when imposing a condition of LM on a person under post-conviction supervision1:

You shall participate in the Location Monitoring Program for a period of __ days utilizing __ technology and shall abide by all program and technology requirements.

___ Radio Frequency (RF) Monitoring;

___ GPS Monitoring;

___ Voice Recognition; or

___ The location monitoring technology chosen at the officer’s discretion.

This form of location monitoring technology will be used to monitor the following restriction on your movement in the community:  

__ You are restricted to your residence every day from ________ to _______ or as directed by the supervising officer (curfew).

__You are restricted to 24-hour-a-day lockdown your residence except for employment; education; religious services; medical, substance abuse, or mental health treatment; attorney visits; court appearances; court-ordered obligations; or other activities as preapproved by the officer (home detention).

__ You are restricted to your residence at all times except for medical necessities and court appearances or other activities specifically approved by the court (home incarceration).

__ You have no residential curfew restrictions; however, must comply with the location or travel restriction as imposed by the court.  Note: this component should be used in conjunction with GPS technology (Stand Alone Monitoring).

[You shall pay ____ (all, part, or none) of must pay the costs of the program as directed by the Court and/or supervising officer.] 

Installation of Location Monitoring Equipment

Under procedural guidance endorsed by the Criminal Law Committee, once the LM equipment to be used is determined, officers are required to install the equipment at the participant’s residence or visit the participant’s residence following an in-office installation to ensure proper installation, verify equipment placement, limit tampering, limit alerts due to improper installation, verify electrical service, verify cellular and/or GPS signal strength, and conduct a range test, if applicable. 

For persons who receive LM as a condition of pretrial release, the installation must be completed on the same day as the court orders bail or the same day the individual is released from custody, unless the court approves a delay.

For persons who receive LM in the post-conviction phase of their federal case, officers should install the LM equipment as soon as possible but not later than 10 business days from the court’s order. LM equipment for higher risk post-conviction participants, including persons convicted of, or who have a history of, sex offenses and any participant with a history of violence, should be installed immediately or as soon practicable. Participants in the FLM programs should have their LM equipment installed immediately upon release from prison or a halfway house.

During any instance of delay of a home visit following an in-office installation due to long-distance travel or after-hours safety concerns, the supervising officer may place the transmitter/tracker on the participant in the office, and the participant may be authorized to complete the receiver/base station installation at the participant’s residence (self-installation), with management approval.  Under procedural guidance endorsed by the Criminal Law Committee, the officer is required to conduct a home visit to verify proper installation within 48 hours or the next business day. For lower risk cases, officers have up to 10 days to conduct the home visit.

Maintaining Contact with Persons on Location Monitoring

Under procedural guidance endorsed by the Criminal Law Committee, the supervising officer is required to conduct a personal community contact with the person on LM every 30 calendar days. This personal contact is necessary to inspect the monitoring equipment and obtain substantive information from individuals in the community who can best provide insight into the participant’s activities, behavior, and overall compliance with the program regulations and conditions of supervision. For lower risk monitoring cases, in which the participant poses no threat of harm to the community, the 30-day personal community contact may be waived for up to six months with management permission, and if the participant is in full compliance. 

Monitoring Location Monitoring and Responding to Alerts

To ensure compliance with the LM program restrictions, LM tests for the participant’s presence at specific locations during prescribed hours. LM equipment is required to track and report key events to the probation or pretrial services officer. Alert notifications on key monitoring events are reported to the officer based on procedural guidance that has been endorsed by the Criminal Law Committee. The procedural guidance establishes time frames by which officers receive alerts and defines those alerts that require immediate responses. 

Under procedural guidance endorsed by the Criminal Law Committee, all officers are required to receive and respond to LM alerts 24 hours a day, 7 days a week. Individual case oversight varies based on the type of equipment used for LM. 

In addition, officers are required, under procedural guidance endorsed by the Criminal Law Committee, to review monitoring reports and GPS mapping daily (7 days a week) for all persons with a history of sex offenses or persons who have been charged with a sex offense in the location monitoring program. The remaining cases require a daily report review each business day. The monitoring reports and GPS mapping review can often reveal patterns of behavior, equipment issues, or problems with adherence to program rules. 

The following chart reflects an officer’s required tasks based on each type of LM equipment.

Officer’s Required Task




Daily review of GPS maps/movement


Chronological notation of GPS map review


*Zone Management


**Investigate drift points


Immediate in-person inspection of GPS tracker upon complete power loss


Monitor GPS tracker charging behaviors


Monitor of beacon/receiver placement in the residence


In-person equipment inspection at every personal contact


Daily review of monitoring reports


Weekly chronological notation of daily report review


The use of virtual monitoring supervision is not part of the national location monitoring contract. Virtual monitoring supervision does not allow for the continuous GPS monitoring of a participant, only random or scheduled reporting. Therefore, virtual monitoring supervision should follow the same guidance given for voice recognition monitoring. If this technology is procured, districts are encouraged to establish local alert notification and investigation standards.

*If GPS is used, the officer must create at least one inclusion zone and monitor inclusion and exclusion zones based on the case specifics and risk factors. Inclusion zones are geographical areas in which a participant’s presence is required during prescribed times (e.g., residence, treatment, district, state). Exclusion zones are geographical areas from which a participant is excluded (e.g., schools, parks, casinos, victim’s residence). If the GPS tracking device leaves an inclusion zone without permission or enters an exclusion zone, an immediate alert is generated and requires an immediate officer response and investigation.  

**GPS drift points can be the result of the following: thickness of the ionosphere, satellite orbit, humidity, or multi-path distortion (GPS bouncing off buildings). The GPS tracker will send an alert to an officer indicating that the participant may have left the approved residence for a short period of time. The officer must investigate the alert for noncompliance and analyze the GPS points for the number of GPS satellites creating the point, point speed, and the pattern of movement.

Last Updated: March 2023

Explore the other sections of the Location Monitoring Reference Guide.

1 The sample language, which was endorsed by the Criminal Law Committee, is also available on the United States Courts website. See Overview of Probation and Supervised Release Conditions document, available at