BAC and breath test accuracy

Most drivers know they may face drunk driving charges in Texas if they have a blood alcohol concentration level of .08% or higher. However, many people do not understand what their BAC level is, the factors that affect it or the accuracy of the devices law enforcement use to measure it. 

A driver’s BAC level refers to the measurement of the ratio of alcohol to blood in his or her body. When people drink beverages containing alcohol, the alcohol gets absorbed into the stomach small intestines and blood vessels, where it then enters the bloodstream and travels throughout the body. According to the AAA DUI Justice Link, the body immediately begins work to metabolize alcohol upon it reaching the bloodstream. As it gets processed, the body eliminates alcohol through the process of oxidation, as well as through the breath and sweat. 

Several factors contribute to how the body processes alcohol, and thus, drivers’ BAC levels. The strength of the alcohol people consume, the size of their drinks and the time they spend consuming alcohol all factor into people’s BAC levels. Producing less of an enzyme that aids in the metabolization of alcohol in the body, women may process alcohol slower than men. Weight also contributes to people’s BAC levels; heavier people tend to have more fluids in their bodies for the alcohol to mix with, which may make their BAC levels lower than a lighter person who consumed the same amount of alcohol in the same amount of time. 

According to, while the professional breath tests law enforcement use to measure drivers’ BAC levels are among the most accurate, several factors may affect the readings of these devices and result in unnecessary arrests. Software glitches, calibration issues and battery problems may cause inaccurate readings. Additionally, drivers using products such as breath fresheners or mouthwash, or having a drink of an alcohol-containing beverage within 15 minutes of testing may also result in false results.