A company that makes personal electronic alcohol monitors that secure to the ankle like a bracelet, is urging courts in the US to make more use of the devices over the holiday season, when there is usually a peak in the rate of alcohol-related offences.

The period between Thanksgiving and New Year is a busy time for courts, and part of the reason is increases in alcohol-related offences, such as driving under the influence (DUI) and domestic violence, according to a statement from Alcohol Monitoring Systems (AMS) in Littleton, Colorado.

Using ankle bracelets as a way to make sure alcohol offenders stay off the booze came to public attention in 2007, when actress, model, and pop singer Lindsay Lohan was photographed wearing one after re-offending for driving over the limit less than two months after crashing her car while under the influence of alcohol.

According to a recent article in New Scientist, these “anklets” are “transforming the way alcohol offenders are dealt with in the US”: over 100,000 people have worn them since they came into use in 2003 and there are currently about 10,000 in use.

Earlier this year, the Probation Department of Montgomery County, New York, announced it was going to start using AMS anklets to monitor the blood alcohol content of convicted drunk drivers.

County Probation Director Lucille Sitterly told NY Daily Gazette, that the plan was for offenders to wear the Secure Continuous Remote Alcohol Monitoring (SCRAM) device throughout the day. Every half hour, the device would measure wearers’ alcohol level through their sweat, and relay the day’s readings to officials in the evening. The device readings are transmitted via a modem installed in the person’s home.

Sitterly said they were attracted to the idea because currently the only way to monitor people ordered to abstain from alcohol when convicted of driving while under the influence, was through a breath analyzer like the ones patrol officers use when they stop a person suspected of driving while intoxicated (DWI).

But the breath analyzers are not very effective, said Sitterly. People can drink alcohol all night, go to their probation appointment the next day, and the analyzer won’t register any alcohol in their system. The problem is growing, as there are more and more offenders every year.

“We have a tremendous felony DWI population in this county,” said Sitterly.

She said they were planning to buy SCRAM devices from the manufacturer, AMS, at a cost of 1,500 dollars each. The offender would also pay a daily fee of 5.30 dollars while wearing the anklet: this would cover the cost of monitoring and relaying the readings, and would form part of the offender’s probation. The amount was well within what they would have been spending on alcohol, she said.

While wearing the anklet, people can take a shower, and play sports, but they can’t go swimming.

Another area where the alcohol monitoring anklet appears to be making inroads is in family court cases.

Kathryn Foster, a judge in Wisconsin’s Waukesha County, who led the state’s first Alcohol Treatment Court, has already put SCRAM into use with a test case where a father volunteered to undergo 30 days of monitoring to counter his ex-wife’s accusations about his drinking, reported the Journal Sentinel last month.

Foster said the anklets could identify parents who were problem drinkers and keep the children out of the interrogation process:

“We don’t like children to be interrogated by the non-drinking parent and to be the reporting person,” said Foster.

Although there have been no independent randomized trials, AMS said that over 70 per cent of offenders who wear the SCRAM anklet don’t violate the terms of their probation or bail.

Some cities report making good progress using the anklets as part of their strategy to cut down alcohol abuse.

In 2005, South Dakota started a sobriety programme whereby judges could order offenders not to take alcohol or other drugs, and forced those on the scheme to wear the SCRAM devices and submit to urine and breath tests.

The overall programme appears to have led to a 43 per cent fall in the rate of alcohol-related accidents and injuries in the state over the last three years.

While officialdom appears to be enthusiastic about the devices and the figures are impressive, there have been reports that the anklet may read false positives.

The technology of the device is such that it can’t tell the difference between ethanol, the alcohol in alcoholic drinks, and other forms of alcohol such as that contained in cleaning fluids. And there have been cases of offenders who claim to have witness supported proof that they were not drinking at the time that the device registered a positive alcohol reading.

But AMS say that they can tell the difference between a false positive and a true positive from the pattern of the readings, although they have not revealed exactly how they do that, except to say that the rate of build up in blood alcohol from drinking rises by less than 0.05 per cent an hour, and when the person stops consuming alcohol, the blood alcohol drops at less than 0.025 per cent an hour. Faster trends than this would be from a contaminant, they say.

According to the New Scientist, there is little independent research on the SCRAM device, but what exists does not contradict what AMS says.

A small study by Paul Marques and Scott McKnight from the Pacific Institute for Research and Evaluation in Calverton, Maryland, published in Alcoholism: Clinical and Experimental Research in April 2009, monitored 22 volunteers who wore the anklet over two to four weeks, in the lab, at home and in bars.

The results showed that the device correctly identified 88 per cent of drinking episodes where blood alcohol went over 0.08 per cent, with no false positive readings. 0.08 per cent blood alcohol is the legal threshold for driving in the US, the UK and other countries.

In 2005, the National Association of Criminal Defense Lawyers in the US published a long article on Alcohol Monitoring Ankle Bracelets that discusses the complexity of relying on measuring blood alcohol content by what transpires through to sweat.

The measurement of alcohol “passing through the skin is complicated as well as attenuated”, they write, and thus blood alcohol content cannot be accurately estimated from perspired alcohol the same way that it is estimated from breath alcohol content.

“Therefore, detection of alcohol consumption using a sweat collection system can only be regarded as a screening tool to help establish continued abstinence. How well it performs even this limited function is of course subject to debate,” wrote the authors.

The article also points to the lack of independent, peer-reviewed studies to support AMS’s claims about the effectiveness of the anklet, and until these are done, the device has “not yet been subjected to an appropriate level of scientific scrutiny, and in order for there to be any likelihood of success this conclusion must be effectively communicated to the Judge”, which one assumes can only add weight to a false positive defense argument.

Marques, who led the small study on the anklet, suggested AMS should tell anklet wearers straight away if they see a positive result come through. That way the wearer has a chance to submit to a breath or urine test to support their case, if they have one.

“If it’s going to affect someone’s freedom then we need confirmation,” Marques told the media, reports New Scientist.

But this could be difficult in practice because of the delay between when the reading occurs and when it is relayed from the modem in the wearer’s home to the AMS monitoring centre.

There have also been some big brother arguments against the device, likening it to the GPS system that keeps track of individual offender’s whereabouts.

On balance though, as the evidence from courts and city schemes continues to show how it brings down the number of DUI and other alcohol related problems, it appears that the anklet has more supporters than critics.

Arthur Lurigio, who studies criminal justice and health at Loyola University in Chicago, told New Scientist that he was sceptical about the science behind the SCRAM anklet device, but welcomed it because “it helps people avoid jail and the stigma of jail”.

Sources: New Scientist, AMS, The Daily Gazette (NY), Journal Sentinel, National Association of Criminal Defense Lawyers.

Written by: Catharine Paddock, PhD