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Breathalyzer Accuracy

If you have been arrested for a DUI in Washington State, you were likely asked to take a breath test. These tests count as evidence against you in court and with the Department of Licensing. The accuracy of the breath test can impact the result of your case. Learn about more about the technology behind this test below.

DUI Breath Test Device

Breath Test Alcohol - Draeger Alcotest 9510

In the state of Washington, the Draeger Alcotest 9510 is the most common device used as the primary evidentiary breath test for DUI cases. The Draeger uses two technologies to measure alcohol on the breath. One of those technologies is the same infrared spectroscopy method used by the older Datamaster machines. The I.R. technology of the Draeger is more sophisticated than that used by the Datamaster. It has an additional “filter” that is used to try to flag the presence of other chemicals on the breath that might cause a false positive. Also, the Draeger uses a separate technology, an electrochemical fuel cell, to come up with an independent alcohol measurement. Because the fuel cell is sensitive only to alcohol, there is less potential for chemicals other than alcohol to cause a false-positive result.

Can breathalyzers be wrong?

Physiological differences between people in the population, such as lung capacity and breathing pattern, to name a few, will cause natural variations in the accuracy and reliability of breath test results. It is also vital to the accuracy of the test that the operator of the machine administers the breath test itself as well as the pre-test mouth check and “observation period” correctly.
Unlike Washington State Patrol breath test technicians, who maintain and repair Washington breath test machines, breath test operators (law enforcement officers) do not have in-depth training on how the machines work.
Most law enforcement officers around the state are certified to operate machines in their area. But their ignorance of the science involved and their relative inexperience in breath testing can cause mistakes during the test administration process. These mistakes may seriously compromise the value of the results of the test.

What can affect a breathalyzer test?

The breath test machine may mistake certain chemicals on a person’s breath for alcohol. The device is not designed to distinguish any interfering chemicals from alcohol, other than acetone.  However, it only recognizes a large amount of acetone on the breath. Thus, a person’s reported breath test result may contain as much as 0.01 of acetone.

In a case where the breath test is 0.09 or under, this means the person may be innocent and wrongly convicted of DUI!  Acetone is one of the most common chemicals found on human breath.

 If you believe that your breath test machine results were affected by a chemical, seek the assistance of Callahan Law, P.S., Inc. We launch an in-depth investigation for clients who believe their test was affected by an interfering chemical.

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What Can Cause a False Positive Breathalyzer Test?

Acetone

Because acetone is so common, the breath test machines are designed to detect it and adjust the result accordingly. However, acetone may still account for the amount of the breath test below .01. For example, if your breath test result was .08 and you had acetone on your breath, acetone may make up for .009 of the result, making the actual value well below .08.

Other types of chemicals that can be reported as alcohol. Chemicals that a person might be exposed to could account for a much higher portion of a breath test result without the machine detecting that the chemical is not alcohol.

Such chemicals include:

Some chemicals may even account for an entire breath test result because breath test machines cannot distinguish them from alcohol at any level.

These chemicals include:

A solvent that you have absorbed through your skin or by breathing vapors from the chemicals may be to blame for a false positive breath test result.

It is essential to talk to an experienced Washington DUI attorney if you were arrested for DUI, and you have are often exposed to solvents.

 

Start your free consultation here

DUI

DOL

License Suspension

Request a DOL Hearing

DOL Hearing Process

Ignition Interlock

Meet our Team

Linda M. Callahan

Stephen P. Grant

Nathan G. Compton

Linda M. Callahan - Avvo Reviews
Linda M. Callahan - Super Lawyer
Linda M. Callahan - Featured on King 5 News

What to Expect at a DUI Arraignment?

“Your first DUI court date is called your arraignment. The arraignment is the formal start of your criminal case that means you’re going to be formally charged with the crime of driving under the influence or any other charges that might be associated with your arrest.” 

Watch this video to learn more.

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If you or a loved one has been arrested for drunk driving, give us a call today to discuss your case.

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Disclaimer: The legal information presented on this site should not be construed to be formal legal advice, nor the formation of a lawyer or attorney client relationship. Any results set forth herein are based upon the facts of that particular case and do not represent a promise or guarantee.  This web site is not intended to solicit clients for matters outside of the state of Washington.