Are Breath Alcohol Tests Always Accurate?

If law enforcement suspects you of drinking and driving, they may pull you over to investigate further. In addition to asking you questions and requesting that you perform a battery of roadside sobriety tests, authorities may ask you to provide a breath sample for testing in order to determine your blood alcohol concentration level. The results of breath tests may serve as grounds for your arrest and, in some cases, evidence of your alleged intoxication at trial. 

According to, however, breath alcohol tests do not always provide accurate readings. 

Machine-related factors 

Several factors relating to the breath testing devices themselves may affect your reading. Breath alcohol test machines require regular calibration, and some use software that needs occasional updates. Putting off recalibrations or updates, as well as incorrectly calibrating these devices may affect their functionality and result in them giving inaccurate readings. Needing a battery replacement or battery charge may also affect breath alcohol test readings. 

Human-involved factors 

Factors relating to you may also cause an error in your breath alcohol test reading. For example, using certain products, such as breath fresheners or mouthwash, may lead to false high BAC test results. Additionally, smoking may also affect the reading. The time between your last drink and the administration of the test may also contribute to inaccurate readings. For example, you may still have trace amounts of alcohol in your mouth if you took a drink 15 minutes prior to giving a breath sample. Consequently, your results may indicate a higher BAC level than you have, which may lead to unnecessary arrest.