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Motorists suspected of driving under the influence must submit to a breath test when a law enforcement official requests one. When a member of the Tennessee highway patrol observes a motorist violating a standard traffic law, the officer may initiate a traffic stop. If a motorist shows signs of impairment while pulled over, he or she may need to blow into a breath test device for a blood alcohol content reading. 

If a test shows a motorist’s BAC is above 0.08%, an officer may place the driver under arrest. Blowing into a roadside testing device, however, may not always provide an accurate BAC level. When an individual faces a DUI charge, it may be possible to avoid a conviction based on an inaccurate roadside BAC reading. 

Factors that may provide inaccurate BAC results 

Several factors may contribute to a motorist showing a higher BAC level than the amount of alcohol he or she actually consumed. Breath mints, mouthwash or cigarettes may interfere with the results produced by a roadside breath test device. 

Depending on how long ago the motorist had his or her last drink, the body may not have completely processed the alcohol. A roadside testing device may misinterpret traces of alcohol remaining in an individual’s breath as part of the blood alcohol content. 

As reported by WebMD, an individual’s weight, hormones or stomach enzymes may affect how quickly the body can break down the alcohol consumed. While drinking a large amount of water generally helps dilute alcohol, certain hormones and the body’s fat stores may slow down the dilution process. 

Roadside testing devices may provide faulty results when incorrectly calibrated. Software glitches and failing to keep batteries charged may also contribute to false BAC levels. 

Proof of impairment 

A DUI conviction from a first-time offense in Tennessee may result in jail time. A prosecutor, however, must first prove impairment at the time of the arrest. By showing how a roadside testing device could have produced an inaccurate reading, a legal defense may help to avoid a DUI conviction.