Breathalyzers are the tool most commonly used in Illinois and across the country to show that a driver was intoxicated when he or she got behind the wheel. Across the country, driving with a blood alcohol concentration of .08 or higher is unlawful and classified as driving under the influence. While blood tests provide the most precise results, breath analyzers are used far more frequently and provide instant results that are largely presumed to be accurate. However, the accuracy of those results could be questionable if the Breathalyzer was not properly calibrated before a driver’s breath was assessed.

In general, courts accept Breathalyzer evidence in order to show that a driver had a BAC that exceeded the legal limit. However, in order for that evidence to be accepted, the police must show that the device is reliable and appropriate for this purpose. When police are unable to show that a breath analyzer has been properly maintained or that the operator has not received proper training, the Breathalyzer results may be excluded from a drunk driving case.

Defective or improperly maintained Breathalyzers can report false positive results. When there is no proof that the machine used works properly, its results may not be used as proof that a driver was intoxicated. While standards vary for Breathalyzer calibration, in most cases, the machine used must be on a list of accepted devices and must be regularly checked to ensure that it is accurate. In addition, the person administering the breath test must ensure that the test is performed properly.

When drivers are charged with OVWI or DUI, challenging the results of a Breathalyzer test might be important. A defense attorney may be able to obtain relevant records to help show that the device was not completely reliable, which might play a role in helping an accused driver avoid a conviction.