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What could affect the accuracy of a breath test?

On Behalf of | Dec 15, 2016 | Criminal Defense, Firm News |

If a law officer pulls you over on the suspicion of drunk driving, you may be facing a breathalyzer test. The amount of alcohol in your bloodstream can be measured when you breathe into this small device. While this test can help officers determine your blood alcohol concentration level with considerable accuracy, the results can be skewed or negated by a variety of factors.

Breath alcohol concentrations

The results of breathalyzer tests show various stages of alcohol-related behaviors. For example, a BAC of 0.02 to 0.03 indicates that a person is mildly relaxed and possibly a bit lightheaded. However, there is no loss of coordination. From 0.04 to 0.06, judgement is slightly impaired, emotions such as excitement or sadness may be exaggerated and inhibitions are lowered. The next stage, 0.07 to 0.09, impairs your ability to operate a vehicle in several ways. Depending on the state, it can be illegal to drive when your BAC level is 0.08 or above.

False positive results

To ensure the effectiveness of a breathalyzer test, you will be asked to wait 15 to 20 minutes af ter drinking or putting anything else in your mouth. Nevertheless, alcohol trapped in dentures or even tongue piercings might cause a false positive. If you are mildly dehydrated, your calculated BAC reading may be as much as 75 percent higher that it would be for a well-hydrated individual. Even small variations in body temperature, air temperature and humidity may be enough to cause an error in the BAC reading. Since a breath test is used to detect ethanol, which is found in alcoholic beverages, results may not be accurate for diabetics and dieters. These people may have high levels of acetone in their systems, which the breathalyzer may register as ethanol and display as a mistakenly high BAC.

Alcohol detection and the IID

In South Dakota, an individual who is on probation following a driving under the influence conviction may be required to have an ignition interlock device or IID installed in his or her vehicle, part of the state’s 24/7 Sobriety Program. The driver must exhale into the tube attached to the device, which is wired to the ignition. If the BAC level is 0.02 or above, the engine will not start. Of course, inaccuracies can apply to IID results just as they can to the breathalyzer used by law enforcement. The results may be skewed if you have just eaten foods that contain alcohol, such as a donut, a cinnamon roll, an overripe banana – even ice cream.

If you need further information about South Dakota DUI laws, including fines, license revocation and the state’s sobriety program, you may wish to contact an experienced attorney who specializes in DUI matters.