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Why breath test results are not always accurate

On Behalf of | Nov 21, 2023 | Criminal Defense

Breath tests measure blood alcohol concentration and play an important role in law enforcement efforts to ensure road safety. However, these tests are not infallible indicators of intoxication.

Various factors can influence the accuracy of breath test results. When this occurs, it can generate misleading conclusions and legal consequences.

Calibration and maintenance

The reliability of breath test equipment hinges on precise calibration and regular maintenance. Failure to adhere to a rigorous calibration schedule can introduce errors into the readings. Even minor deviations in the calibration process can yield inaccurate BAC measurements. This is especially significant considering that breath test machines are sensitive instruments that require meticulous attention to detail. Without consistent calibration and maintenance, the results of a test may be unreliable.

Individual variations in metabolism

Human metabolism varies significantly from person to person. Breath test results assume a standardized rate of alcohol metabolism. However, this assumption does not account for the wide range of metabolic rates among individuals. Factors such as age, weight and overall health can influence how quickly the body processes alcohol. As a result, someone with a slower metabolism may register a higher BAC on a breath test even if they have consumed the same amount of alcohol as someone with a faster metabolism.

Environmental factors

The environment in which someone takes a breath test can also impact its accuracy. Substances like mouthwash or breath fresheners containing alcohol can artificially inflate BAC readings. Additionally, air temperature can affect the precision of breath test results. Extreme temperatures, whether hot or cold, may lead to inaccuracies in readings. Law enforcement officers must be vigilant in controlling these environmental variables to maintain the reliability of test results.

Medical conditions and diet

Certain medical conditions and dietary choices can also interfere with the accuracy of breath test results. Individuals with conditions such as diabetes or acid reflux may produce elevated BAC readings, unrelated to alcohol consumption. Moreover, low-carb diets, such as ketogenic diets, can generate acetone in the breath, leading to falsely high BAC readings.

Breath tests are valuable tools that help maintain public safety but have limitations. While Medical News Today reports that the accuracy of law enforcement breath tests and at-home breath tests are similar in about 94% of circumstances, neither type of breath test is foolproof.