Potential False Positive Alcohol Readings on SCRAM Devices

There are several different devices that test for alcohol concentration. As a Kansas criminal defense attorney I regularly deal with these instruments. For example, there are times when I have to explain a false positive on an ignition interlock device, Intoxilyzer 9000, PBT, UA, or ETG test. One very common instrument is the SCRAM unit. This is regularly used as a sanction for alcohol use while on probation or diversion. Additionally, it is regularly utilized in pre-trial services as a condition of bond, especially for DUI charges. ​

What is SCRAM?

SCRAM stands for Secure Continuous Remote Alcohol Monitor. It is made in Littleton, Colorado by Alcohol Monitoring Systems, Inc. The SCRAM is a small device that is secured around a person’s ankle and continuously tests them for alcohol usage. It does the testing via a transdermal alcohol sensor that then reports the TAC (Transdermal Alcohol Concentration).

About Inaccurate Readings on SCRAM

While the SCRAM can be a helpful monitoring device, it does have some issues. First, it can overstate the alcohol concentration.

About 1-5% of the alcohol consumed by a person is unmetabolized and exits the body unchanged. The SCRAM measures this alcohol sweated out through the skin. The problem is that it assumes that the person is eliminating just 1% of the alcohol without metabolizing it. This means that when the internal calculation is completed, it will provide a Transdermal Alcohol Concentration (TAC) reading that can actually up to 5 times higher than reality.

The second problem is that sometimes devices provide false positives based on readings that are in fact not alcohol. There are times when the SCRAM machine shows alcohol, but it isn’t alcohol. To address this issue, one needs to look at the numbers being shown and compare them to realistic absorption rates and elimination rates.

How to Disqualify Readings on SCRAM

One way of disqualifying alcohol as the source is from the SCRAM reading that immediately follows. If the elimination rate is non-linear, as compared to a more constant elimination rate, that is indicative of something other than alcohol causing the reading. While it varies by person, a typical elimination rate is .018 per hour for alcohol. This elimination rate of ethanol is constant, adhering to zero-order elimination kinetics. This is actually rare as most drugs are eliminated based on first-order kinetics which decreases exponentially, depending on the concentration of drugs. So, by analyzing the elimination rate, if the alcohol results lower at varying rates, that is an indication that it is not really alcohol.

Furthermore, if the elimination rate is too, quick, that is another factor. While .018 per hour is typical, .064 is the highest elimination rate that has been recorded. This was reported by Neuteboom and Jones in 1990. Alcohol elimination occurs through a metabolic function occurring mostly in the liver, stomach, and small intestine. These clearance rates of alcohol rely upon the varying types and amounts of Alcohol Dehydrogenase Enzyme (ADH enzyme) found in the body, which varies from person to person. Generally, alcohol is eliminated from the blood 0.013 – 0.022 grams per hour. It is lower for people who are fasting, on low-protein diets, or malnourished. On the other hand, the elimination rate is higher for people who regularly use alcohol. Alcoholics can have elimination rates of 0.036 – 0.040 grams per hour. This was reported by Jones in 1996.

As one can see, to be fair in testing, one’s specific body, their individual elimination rate, differing absorption conditions should be considered. However, this is rarely done.

Not only is the elimination rate an issue, but so is the absorption rate. It takes time for the body to first consume the alcohol and then absorb the alcohol. Yes, a person can quickly drink alcohol, as we have all seen. However, the more quickly the alcohol is consumed, the longer it takes to absorb. Whatever speed it is consumed though, it then takes time for the body to absorb it. So, if there is a sudden high reading on a SCRAM, without prior numbers going up, then it isn’t alcohol. In 1985 Dr. Dubowski reported that it takes between 9-192 minutes for the body to fully absorb alcohol.

​Another problem that can lead to false positives come not only from within the body but also from the chemicals that may be in the air around us. For example, painters, yard workers, employees handling static guard, and cleaners handling chemicals can run across problems due to false positives. It should be noted that ethanol in the air is very volatile evaporating at room temperature and its elimination rate is not linear. i.e. the higher the percentage of ethanol in the chemical compound, the higher the elimination rate will be early on.

Let an Experienced Johnson County DUI Lawyer Explain

Judges generally want to do what is right, but in my experience as an experienced DUI lawyer in Johnson County and throughout Johnson County, I have learned that they sometimes do not know about these scientific issues. While a learned treatise can be helpful evidence and teaching material, sometimes you need to bring in a qualified scientist to explain the situation or provide an expert opinion letter on the matter. If you need legal counsel on inaccurate results from a SCRAM device contact Martin & Wallentine, LLC for a case evaluation with an Johnson County DUI attorney. Call (913) 764-9700.

Related Reading

Contact Martin & Wallentine, LLC or call (913) 764-9700 for a consultation with a DUI lawyer. 

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