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Program Profile: Pretrial GPS Supervision of Intimate Partner Violence Defendants (Western Region, United States)

Evidence Rating: No Effects - One study No Effects - One study

Date: This profile was posted on June 14, 2018

Program Summary

This is a court-based, pretrial, GPS supervision intervention for defendants arrested for intimate partner violence offenses. The program is rated No Effects. Program participants showed no statistically significant reductions in risk of rearrests, domestic rearrests, or failure to appear in court. However, the program did show statistically significant reductions in defendants’ risk of failure to appear at meetings with pretrial services.

Program Description

Program Goals/Target Population
This program is a court-based, pretrial, global positioning system (GPS) supervision intervention, implemented in a western region of the United States, intended to monitor the movements of defendants arrested for intimate partner violence (IPV), to reduce pretrial misconduct such as rearrests, failure to appear in court, and missed court meetings. Defendants are eligible for GPS supervision based on a judge’s discretion.
Program Components
Defendants who are assigned to GPS supervision report immediately to pretrial services, where they are informed that their movements will be tracked in real time. Defendants are expected to participate in telephone and in-person check-ins and case management meetings. They are monitored by a centralized monitoring center and a pretrial officer.

The GPS technology consists of a one-piece unit placed on the defendant’s ankle. Exclusion zones are then set in keeping with the terms of the victim’s protection order, issued immediately after an IPV arrest. The outer exclusion zone is a 1,000-foot radius that surrounds a victim’s routine location (i.e., home, work, or children’s school). The inner exclusion zone consists of a 300-foot radius that corresponds to the requirements of a standard mandatory protection order, which requires a defendant to stay at least 100 yards away from the victim. Additional exclusion zones, up to 1,000 feet, can be set by the supervising officer with assistance from the victim or victim advocate.

The unit captures every minute that a defendant is not in violation and every 15 seconds when a defendant is in violation of the protection order exclusion zones. If a defendant is not in violation, the GPS information can be accessed on an as-needed basis. However, a defendant in violation of the exclusion zones will trigger a notification to the presiding officer’s cell phone, computer, and e-mail. A proprietary software, used by the pretrial officer, can send a pre-recorded verbal notification and an audible “ping” to the defendant’s cellular device at any time. The defendant is required to acknowledge these notifications. As pretrial officers do not have arrest power, they must rely on law enforcement to do welfare checks and make an arrest. Violations are then reported to the prosecutor’s office.

Evaluation Outcomes

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Study 1
Failure to Appear in Court
Grommon and colleagues (2017) found that there was no statistically significant difference between the treatment group on pretrial GPS supervision and the control group on basic pretrial supervision, on risk of failure to appear in court.  

There was no statistically significant difference between the treatment and control groups on risk of rearrest.

Domestic Rearrests
There was no statistically significant difference between the treatment and control groups on risk of rearrest for a domestic violence charge.
Failure to Appear in Meetings
The treatment group had a lower risk of failing to appear at meetings with pretrial services, compared with the control group. This difference was statistically significant.
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Evaluation Methodology

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Study 1
Grommon and colleagues (2017) used a retrospective quasi-experimental design to examine the impact of pretrial global positioning system (GPS) supervision on defendants arrested on intimate partner violence (IPV) charges. The study was conducted in a pretrial services division of a city and county community corrections department in a large jurisdiction, of approximately three million residents, in the western region of the United States. The intervention was evaluated to examine failure to appear in court, pretrial services meetings, and rearrests outcomes, compared with defendants assigned to pretrial supervision without GPS technology.
The study consisted of a total of 1,483 defendants assigned to either GPS supervision or basic pretrial supervision. Of the defendants who participated in the study, 85 percent were male, 71 percent were white, and 37 percent were Hispanic, and the average age was 34 years. The treatment group (N=573) received an ankle unit that monitored a defendant’s movements while awaiting trial. An assigned pretrial officer was notified when a defendant violated any of the exclusion zones. The control group (N=910) received traditional pretrial supervision but was still required to have contact with pretrial services through telephone check-ins and case management meetings.

Two different information systems were used to maintain defendant records. One system-maintained records about defendants referred to the court and documented the period between jail booking and the bonding decisions made at the initial hearing. The second system detailed court and supervision activity. Both systems were used to access demographic, criminal history, instant offense, risk assessment, bond recommendation, and bond order information.

Four different outcomes were measured to determine pretrial misconduct. Failure to appear in court was defined as a defendant’s failure to appear at a scheduled court hearing. Failure to appear at a meeting was defined as a defendant’s failure to attend a scheduled meeting with the assigned pretrial officer. Rearrests were defined as any new arrest for any new offense. Domestic rearrests were defined as any new arrest for a domestic violence offense, including violations of protection or court orders.

A Cox regression model was used to compare pretrial misconduct between those defendants on GPS supervision and those receiving basic pretrial supervision. A chi-square and ANOVA models were used to assess baseline differences between the treatment and control groups. There were statistically significant differences between treatment and control groups at baseline. Defendants in the treatment group had more serious charges, higher risk scores, more contact with the criminal justice system, and received higher bond amounts. The study addressed the limitations by using different methods to reduce bias in the sample, including propensity score matching strategy using the Mahalanobis distance and the marginal mean weighting through stratification (MMW-S). It is the MMW-S procedure that produced the most equivalent comparison group, to assess the effect of GPS supervision. The outcomes presented below relate to the MMW-S method. No subgroups were analyzed.
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There is no cost information available for this program.
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Evidence-Base (Studies Reviewed)

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These sources were used in the development of the program profile:

Study 1
Grommon, Eric, Jason Rydberg, and Jeremy G. Carter. 2017. “Does GPS Supervision of Intimate Partner Violence Defendants Reduce Pretrial Misconduct? Evidence from a Quasi-Experimental Study.” Journal of Experimental Criminology 13(4):483–504.

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Additional References

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These sources were used in the development of the program profile:

Carter, Jeremy G., and Eric Grommon. 2016. “Police as Alert Responders? Lessons Learned about Perceived Roles and Responses from Pretrial GPS Supervision of Domestic Violence Defendants.” Policing: A Journal of Policy and Practice 10 (4): 361–77.

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Related Practices

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Following are practices that are related to this program:

Pretrial Interventions for Ensuring Appearance in Court
During the pretrial process, defendants may be released on certain conditions. To ensure that released defendants show up to their court date, jurisdictions have used three strategies: 1) court-date reminder notifications, 2) bonds, and 3) supervision in the community. The goal of is to reduce the failure-to-appear rates of defendants. Across the three strategies, the practice is rated Promising for decreasing failure-to-appear rates, but rated No Effects for reducing arrest rates.

Evidence Ratings for Outcomes:
Promising - One Meta-Analysis Justice Systems or Processes - Failure-to-Appear
No Effects - One Meta-Analysis Crime & Delinquency - Multiple crime/offense types
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Program Snapshot

Gender: Both

Race/Ethnicity: Hispanic, White, Other

Geography: Urban

Setting (Delivery): Courts

Program Type: Violence Prevention, Electronic Monitoring

Targeted Population: Serious/Violent Offender

Current Program Status: Active