by ybriw
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Can Electronic Monitoring Actually Save Your County Money on Pretrial Detention?
Yes — but only when substituting for detention, not for unconditional release. Washington DC’s pretrial EM program documented costs of roughly $750 per participant per year (ranging from $460 to $1,070), generating approximately $580 in local savings and $920 in federal savings per participant compared to detention. Cook County found EM saved approximately $8,200 per defendant versus incarceration and reduced failures to appear by 10.6 percentage points compared to unconditional release. The critical qualifier: EM generates savings when it keeps people out of jail who would otherwise be detained. Using EM on defendants who would have been released anyway — so-called “net-widening” — adds cost without reducing jail population.
The Scale of Pretrial Detention Spending
Approximately 60–70% of individuals held in US jails at any given time are detained pretrial — they haven’t been convicted of anything. They’re awaiting trial, unable to post bail or denied release. For county governments, this pretrial population is the single largest driver of jail operating costs.
The math is straightforward. The average cost to house a pretrial detainee ranges from $75 to $200+ per day depending on jurisdiction, or roughly $27,000 to $73,000 per year. Electronic monitoring costs $2 to $15 per day depending on device type and monitoring level — an order of magnitude less. Even at the high end of EM costs and the low end of detention costs, the ratio is roughly 1:5.
But cost per person only matters at scale. Consider a mid-sized county jail with 800 beds, 500 of them occupied by pretrial detainees. If EM allows safe release of just 50 of those defendants — a 10% diversion rate — the annual savings range from $1.4 million to $3.7 million, depending on your per-diem jail costs. That’s after accounting for the cost of the EM program itself.
What the Research Shows
Washington, DC — The Urban Institute Study
The Urban Institute evaluated DC’s pretrial EM program and found:
- EM cost: ~$750/participant/year ($460–$1,070 range)
- Local savings: ~$580/participant from avoided detention
- Federal savings: ~$920/participant (DC’s detention facilities are federally funded)
- EM reduced new arrests by 24% compared to the control group
- Societal benefit from averted victimization: ~$3,800/participant
The DC program targeted defendants who would otherwise have been detained — the population where EM substitution creates actual savings. When EM is used instead of simple release, costs go up without proportional jail reductions.
Cook County, Illinois — Columbia University Analysis
Cook County’s analysis of EM as a pretrial option found:
- EM saved approximately $8,200 per defendant versus continued detention
- EM reduced failures to appear by 10.6 percentage points compared to unconditional release
- EM reduced new pretrial cases by 7.4 percentage points versus unconditional release
This is the dual benefit: EM costs less than jail AND produces better compliance than releasing defendants with no supervision at all. For pretrial services managers, EM occupies the middle ground between the two extremes.
San Francisco — California Policy Lab
San Francisco’s pretrial EM use expanded more than twenty-fold between 2017 and 2021, growing from an average of 75 cases per year to over 1,650. However, the California Policy Lab’s evaluation revealed operational challenges:
- 60% of participants were terminated prematurely for non-compliance
- Over one-third of monitored individuals were unhoused or unstably housed
- 85% were booked on felony charges with a median of five prior jail bookings
- Over 65% were rated at the highest risk category
San Francisco’s experience is a caution: cost savings only materialize when the program retains participants. A 60% premature termination rate means those individuals return to detention — negating much of the projected savings and consuming officer resources on enrollment, monitoring, and re-arrest.
Bernalillo County, New Mexico
A 2024 study from the University of New Mexico’s Institute for Social Research evaluated the costs and benefits of pretrial detention and release in Bernalillo County. Research consistently finds that pretrial detention may produce short-term incapacitation effects but has longer-term criminogenic effects — detained defendants are more likely to reoffend after release than comparable defendants who were not detained.
Building the Business Case for Your County
When presenting an EM program to county commissioners or budget committees, structure the cost analysis around these four components:
1. Direct Cost Comparison
| Cost Category | Pretrial Detention | GPS Electronic Monitoring | BLE/Smartphone Monitoring |
|---|---|---|---|
| Per-person daily cost | $75–$200+ | $5–$15 | $2–$5 |
| Annual cost per person | $27,000–$73,000+ | $1,825–$5,475 | $730–$1,825 |
| Equipment investment | N/A (facility already exists) | Moderate | Low |
| Staffing model | 24/7 corrections officers | Monitoring center + field officers | Automated alerts + periodic check-ins |
2. Avoided Jail Expansion
Building new jail capacity costs $50,000–$150,000 per bed in construction alone, plus ongoing operational costs. An EM program that diverts 50–100 defendants from pretrial detention can defer or eliminate the need for a multi-million dollar jail expansion. This is often the strongest argument for county commissioners: EM doesn’t just reduce operating costs — it avoids capital expenditure.
3. Revenue and Compliance Benefits
Defendants on EM can maintain employment, pay taxes, support families, and meet financial obligations (including bail or restitution payments) — none of which is possible while detained. The DC study estimated $3,800 per participant in societal benefit from averted victimization alone. Employed defendants on EM also generate economic activity that detained defendants cannot.
4. Risk-Based Implementation
Not every pretrial detainee is a candidate for EM. Target the population where data supports safe release with monitoring. Validated risk assessment tools (like the PSA, VPRAI, or locally calibrated instruments) identify defendants who are medium-risk: too high for unconditional release, but manageable outside jail with electronic supervision. This is where EM creates the maximum cost-benefit ratio.
Avoiding the Net-Widening Trap
The most common failure mode for EM programs isn’t technology — it’s target population selection. Virginia’s Department of Criminal Justice Services explicitly warns against using EM on low-risk offenders who could be safely released without monitoring. When EM is applied to defendants who would otherwise be released on recognizance, the program:
- Adds cost without reducing jail population
- Creates compliance failure points (charging, curfew, zone restrictions) that can lead to re-incarceration
- Consumes officer and monitoring center resources on low-risk cases
- Generates misleading metrics — high enrollment numbers with no jail bed savings
The discipline is straightforward: only deploy EM as a substitute for detention, not as a substitute for release.
Related Resources
GPS ankle monitoring costs agencies $5-15 per offender per day, compared to $137-$550 per day for pretrial detention. Washington DC documented total annual EM costs of approximately $750 per participant. The true cost includes device hardware, monitoring platform fees, cellular data, strap replacements, false alert labor, and staff overhead — with false alert labor often exceeding hardware costs in programs using high-false-positive tamper detection.
Selecting an ankle monitor vendor requires evaluating six weighted criteria: anti-tamper technology reliability (30%), total cost of ownership including false alert labor (25%), monitoring platform capabilities (20%), field deployment track record (15%), and training/implementation support (10%). This guide provides a scoring framework agencies can adapt for RFP evaluation committees.
Effective EM staff training covers four domains: device operations (installation, troubleshooting, charging), monitoring center protocols (alert triage, escalation, documentation), field supervision skills (offender compliance, home visits, violation response), and legal/ethical framework (Fourth Amendment, data privacy, evidence handling). The UK Inspectorate of Probation found that programs with structured training delivered measurably better outcomes than those that treated EM as plug-and-play technology.
Launching an electronic monitoring program requires more than buying devices. Virginia's DCJS and the BJA/APPA User's Guide identify three phases: defining program purpose and target population, developing policies and screening criteria, and selecting equipment through structured procurement. The biggest implementation mistake is net-widening — monitoring low-risk offenders who don't need it.