People who have been pulled over on suspicion of driving under the influence of alcohol may have taken a breath test. This handheld device is used to determine whether the driver is intoxicated by measuring the amount of alcohol present in their breath; however, studies show that these tests may not always give accurate results.

Credible studies conducted by LaBianca, Simpson, Thompson compared the BAC results that are indirectly obtained from a Breathalyzer test machine to the BAC results acquired through a blood test. They found a 50 percent margin of error in the Breathalyzer device’s ability to convert the alcohol content found in a breath sample to the actual amount of alcohol present in the blood. A 0.1 percent BAC reading given on a Breathalyzer device may translate to an actual BAC level of anywhere between 0.05 and 0.15 percent. Since the legal BAC limit in Wisconsin is 0.08 percent, some drivers may be wrongfully arrested on suspicion of DUI.

The State University of New York at Potsdam reports that breath tests measure more than the ethyl alcohol that is found in alcoholic drinks. It also picks up substances containing a methyl group structure. Common substances found in the environment, such as paint removers, gasoline, tobacco smoke, cleaning fluids and dirt, can affect breath test readings. When a device is not calibrated properly or is used incorrectly, it can also give erroneous results.

Due to these proven inaccuracies, many law enforcement departments in Wisconsin use blood tests to determine a person’s alcohol toxicity level. In cases where a blood test is not administered, people may question whether or not the results from their breath test are accurate. This information should be used for general purposes only and should not be taken for legal advice.