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Are breath alcohol tests reliable?

Providing an estimation of the amount of alcohol in drivers’ blood, the authorities largely rely on breath alcohol tests during drunk driving stops. If the results indicate you have a blood alcohol content over the legal limit of 0.08%, you may be arrested for driving under the influence or while intoxicated. Unfortunately, these tests do not always provide reliable readings. Consequently, you may find yourself facing an unnecessary arrest, which could have serious implications on your freedom and future.

Since the results of breath alcohol tests may serve as grounds for your arrest and as evidence against you at trial, it behooves you to understand the factors that may affect their accuracy.

Human factors

According to, several human factors may affect the accuracy of breath alcohol tests. These include smoking prior to providing a breath sample, as well as using alcohol-containing products such as breath fresheners or mouthwash. You may also receive a false high reading if you took a drink of an alcoholic beverage up to 15 minutes before giving your breath sample. In such cases, trace amounts of alcohol may remain in your mouth and cause the device to give inaccurate results.

Device factors

While the fuel cell breath alcohol testing devices used by law enforcement rank among the most accurate, some factors relating to the devices themselves may cause false readings. Battery-operated, these devices may give inaccurate results when needing a charge or a battery replacement. Additionally, many devices require regular calibration and software updates. Failing to properly calibrate or to perform the necessary updates may also affect breath alcohol test readings.