How the SCRAM Ankle Bracelet Measures Blood Alcohol

This controversial device also detects tampering efforts

Alcohol Metabolism Chart
Transdermal Testing Explained. SCRAM Systems

Electronic ankle bracelets have been an effective way to monitor people under house arrest, and are now used to measure alcohol consumption by repeat offenders. The Secure Continuous Remote Alcohol Monitor, or SCRAM, reads the blood alcohol content of the person wearing it every 30 minutes and reports those readings to supervising agencies.

The SCRAM is not only used by the judicial system but has also been used with some success by alcohol treatment providers to monitor the alcohol consumption of patients.

The SCRAM is used to help patients maintain compliance with abstinence-based programs and identify patients that need further intervention.

Technology has advanced significantly since SCRAM first began offering alcohol monitoring systems to agencies in 1997. The company now offers two different devices - one that measures blood-alcohol content through the skin and another that provides remote breath testing to supervising agencies.

Different Types of SCRAM Monitors

The device that tests alcohol consumption through the skin (transdermal testing) is called SCRAM CAM (continuous alcohol monitoring). The device is strapped around the offender's ankle and sends test results to the base unit located in the offender's home.

Originally, the base unit communicated the test results to the supervising agency through the offender's telephone landline. Now the base unit can use cell phone or Internet connections.

If the offender is sentenced to home confinement or is given a curfew, the SCRAM CAM can also monitor for compliance. The device eliminates the offender's ability to miss a test or drink around testing schedules.

SCRAM Remote Breath Tester

A remote handheld device takes a photograph of the person has they blow into the machine, and uses facial recognition software to make sure the person taking the test is the person under supervision.

The remote breath tester also contains GPS technology which will record the GPS coordinates of the machine each time it conducts a test. If the offender misses a scheduled test, the machine records the GPS location at the time of the missed test.

Problems with SCRAM Monitors

In the early years of its use, the SCRAM devices had some limitations and problems. Some of these problems included:

  • Being too sensitive and giving false positives
  • Devices could be removed without providing an alert
  • Would not detect some "low level" drinking events
  • Could report false tamper alerts

These problems were noted in a series of studies of the alcohol monitoring devices funded by the National Highway Traffic Safety Administration (NHTSA). The research was conducted by programs monitoring drunk drivers and other alcohol-involved offenders several states.

One of the problems reported with alcohol monitoring devices was the reluctance of probation officers and caseworkers to participate in the program because they did not believe they would work.

In the New York 8th Judicial District, they found that if they convinced the doubting agents to wear the devices and test them themselves, they soon became advocates for the program.

SCRAM Can Lower Recidivism Rates

Another NHTSA-funded study looked at the use of SCRAM and recidivism among drunk driving offenders and concluded that the device was effective in monitoring alcohol abstinence. It found that the device could cut down on the need for probation or other court officers to do in-home monitoring, leading to reduced costs. 

The study also reported that offenders who remain abstinent while going through alcohol treatment programs had better outcomes compared to those who were not monitored and not abstinent.

Sources:

McKnight, A. S., et al. "Transdermal alcohol monitoring: Case studies." (Report No. DOT HS 811 603). Washington, DC: National Highway Traffic Safety Administration. (2012, August).

Tison, J., et al. "Comparative study and evaluation of SCRAM use, recidivism rates, and characteristics." (Report No. DOT HS 812 143). Washington, DC: National Highway Traffic Safety Administration. (2015, April)

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