Limitations On EtG Tests As Proof Of Consumption

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Anyone charged with drunk driving (DUI / OWI) or a related MCL 257.625a offense in Michigan will, in virtually every case, be subject to bond conditions that include random testing for alcohol and drugs. Similarly, anyone ultimately convicted of drunk driving (DUI / OWI) or a related MCL 257.625a offense will, in virtually every case, be subject to terms of probation that include random testing for alcohol and drugs.

The type of testing can vary from jurisdiction to jurisdiction. Some courts will order random PBTs while others will require the individuals subject to testing to provide urine samples to test for alcohol and drugs. It is in the latter cases where problems can develop due to the inability of the testing process to distinguish between incidental exposure to alcohol and intentional consumption.

The problem is further compounded by the fact that there is currently no known cutoff that can differentiate between incidental exposure to alcohol and beverage alcohol consumption. The most prevalent test for alcohol consumption utilized within the criminal court context is EtG tests.


Alcohol biomarkers are physiological indicators of alcohol exposure or consumption. Ethyl glucuronide (EtG) is considered to be a direct alcohol biomarker because it is an analyte of alcohol metabolism. Consequently, EtG testing has been promoted and marketed by testing laboratories as a method to detect alcohol consumption in individuals.

As a further consequence, courts routinely accept at face value the results of EtG tests as “proof positive” that an individual has violated bond conditions or a condition of probation by intentionally consuming alcohol. However, the science underlying the test fails to support the claims of the testing companies and calls into question the appropriateness of considering the results of EtG tests in bond or probation violation hearings.

In September of 2006, the United States Department of Health and Human Services issued an advisory bulletin that asserted: “Currently, the use of an EtG test in determining abstinence lacks sufficient proven specificity for use as primary or sole evidence that an individual prohibited from drinking, in a criminal justice or regulatory compliance context, has truly been drinking. Legal or disciplinary action based solely on a positive EtG, or other test discussed in this Advisory, is inappropriate and scientifically unsupportable at this time.”

The Advisory was predicated on clinical findings that:

  • No laboratory test is 100% accurate and clinical correlation is critically important.

  • Studies show some people produce more EtG for a given dose of alcohol than others.

  • Positive EtG tests are not proof of intentional alcoholic beverage consumption since low level positive tests have been shown to occur due to incidental exposure.

  • Some people have a condition whereby they produce ethanol endogenously (“auto brewery syndrome”) that can give rise to a positive test in the absence of intentional consumption.

It was further noted that: “[A]t issue is whether exposure to alcohol or to the vapors of alcohol in many commercial products, such as personal care items, over-the-counter medications, cleaning products, desserts, wine vinegar, and the like or combinations of these products may cause elevation of EtG or EtS that could be a return to drinking. Exposure to these products combined with possible influences of individual variables such as gender, age, and health status on alcohol biomarker responses has not been adequately studied to date.” Id.

EtG tests are performed on a urine specimen supplied by the testing subject. The problem is that research has shown EtG tests may become positive shortly after even low-level exposure to alcohol or alcohol based products and remain detectable for days. Indeed, “[B]ecause of the purported high sensitivity of these tests, exposure to alcohol that is present in many daily use products might result in a positive laboratory test for these biomarkers.” Id.

The lesson to be learned is that positive results of EtG tests can be successfully challenged in court.

Any individual who is threatened by a bond or probation violation hearing should immediately contact an experienced Michigan DUI defense lawyer who has taken the time to study and understand the complexities and limitations of direct biomarker testing.

For those interested in additional references to materials on the value of EtG testing:

  • Helander A, Dahl H. Urinary tract infection: a risk factor for false-negative urinary ethyl glucuronide but not ethyl sulfate in the detection of recent alcohol consumption. Clin Chem. 2005 Sep; 51(9): 1728-30

  • Helander A, Olsson I, Dahl H. Postcollection synthesis of ethyl glucuronide by bacteria in urine may cause false identification of alcohol consumption. Clin Chem. 2007 Oct; 53(10): 1855-7

  • Wurst FM, Dresen S, Allen JP, Wiesbeck G, Graf M, Weinmann W. Ethyl sulphate: a direct ethanol metabolite reflecting recent alcohol consumption. Addiction. 2006 Feb.; 101(2): 204-11

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