PinUnder Minnesota law (Minn. Stat. Chap. 169A), if you are stopped for suspicion of driving under the influence or otherwise impaired by drugs or alcohol and blow higher than .08 in a breathalyzer then you will be charged with DWI.

Breathalyzer tests assume that the air measured is deep lung area from the alveoli; however, in reality, breath air contains a sample from the entire respiratory system. Consequently, alcohol molecules can interact with mucus and other substances in the mouth and throat, thus altering the amount of alcohol measured in any given breath sample.

The only truly accurate test to measure blood alcohol content (BAC) is a blood test; however, pursuant to US Supreme Court rulings, law enforcement officers must obtain a warrant before obtaining a subject’s blood. Because breath tests cannot be refused under the state’s implied consent law without additional criminal and administrative penalties, breathalyzers are the most common type of test used.

With the extreme importance on this single number, what should you do if your breathalyzer result is inaccurate?

When to call breathalyzer test results into question

There are several reasons why a breath test may be inaccurate. Consulting with a knowledgeable and experienced DWI attorney who is aware of these factors goes a long way in ensuring you aren’t charged, prosecuted, and convicted for a crime you didn’t commit.

Use of the wrong type of machine

There are, essentially, two types of breathalyzer machines: a platinum fuel cell breathalyzer and a semiconductor sensor breathalyzer. The first type is more accurate because of its professional grade materials and history of consistent and accurate results. Conversely, the semiconductor sensor breath machine is typically powered by tin oxide which is both less expensive and less accurate. These sensors respond to body ketones—or natural biproducts of fat oxidation—which may create a false positive for alcohol in a test. This false positive doesn’t occur in platinum fuel cell machines because they are alcohol specific.

Whereas the second type of machine is adequate for preliminary alcohol measurements, it is sorely inefficient as evidence in a legal case. Most police departments use platinum fuel cell breath machines; however, if this is not the case, you may have a good case challenging your test results.

Faulty calibration

Like most oft-used machinery, breathalyzers need regular maintenance to remain in optimum working order. If a machine hasn’t been properly and/or recently calibrated—with documentation to prove this—then a test result could be thrown out of court as inaccurate.

The test is only administered one time

Administering a breath test once is a recipe for disaster. Many things can vary in a single test, thus resulting in an inaccurate result. Perhaps the operator wasn’t trained adequately enough. Or the machine could be faulty. Finally, the subject of the test may not have exhaled powerfully enough for the test to register properly. When a test is conducted multiple times with consistent results, then there is a higher probability of accuracy.

Lung capacity factors

Breath machines are calibrated according to an adult’s average lung capacity and, therefore, a test could be biased based upon certain individuals. Younger males who are taller tend to have larger lungs than others and because they expel more molecules from their lungs, may produce higher alcohol content readings. Similarly, those with smaller lungs may have to take deeper breaths and may also inadvertently end up expelling more molecules than in the case of a normal breath.

The condition of one’s lungs can also affect a breath test. Certain diseases naturally decrease lung capacity. Illnesses that produce excess mucus in the lungs like bronchitis and pneumonia will skew test results because mucus absorbs alcohol molecules. Other illnesses like asthma, fibrosis, and emphysema constrict lung capacity and cause subjects to produce a smaller sample which may be incorrect.

Other health conditions

Still other diseases affect one’s breath. Diabetes patients tend to have a higher acetone concentration in their breath. Since breath machines look at acetone as ethanol, the test may yield a false positive. Compounding the problem is that many individuals with diabetes are undiagnosed. Acid reflux and GERD also have a higher propensity for yielding a false positive. Because these diseases facilitate stomach acid travel up the esophagus, it may contribute to mouth alcohol, thus making someone’s BAC reading higher even if that person is not legally intoxicated.

Foreign substances in one’s mouth

Several common substances can disrupt breathalyzer test results. Products with high alcohol contents such as mouthwashes and cough syrups/drops can be misread, and other chemicals in such products as hair products, cleaning materials, and cigarettes may also be misread and lead to a false positive.

Diet

Similarly, diet can affect a breath test. High protein diets tend to produce acetone in the breath which can be falsely read as alcohol in a breath test.

Environmental factors

Certain people may be exposed to certain chemicals that may manifest as a false positive for alcohol. Paints, cleaning solutions, adhesives, lacquers, and plastics all produce fumes that may be inhaled and contribute to a false positive reading in a breath test.