Breath tests are used by law enforcement, typically the police officer who stops you, to determine your blood alcohol level (BAC). If your BAC is .08 more, then the Tennessee law provides that you are guilty per se of driving under the influence. While a BAC below .08 does not qualify as a per se DUI, prosecutors will often still push these cases, especially if they believe that illicit drugs were used along with the alcohol.  The police usually ask you to submit to field sobriety tests before asking you to submit to a breathalyzer test.

Breathalyzer tests are estimates of the alcohol in your blood through your breath. The police generally use larger breathalyzer devices which are reliable enough to use in court – if they have been properly inspected and calibrated.

Different types of breathalyzers

Ethanol is the alcohol in most consumable alcoholic beverages. It’s easily absorbed through the stomach and into the blood. Per Forbes, “Each time you breathe a small amount of the alcohol in your blood vaporizes and is passed into the alveoli in your lungs and passed out of your body. The more alcohol you have consumed, the greater the amount that passes out.” Breathalyzer machines can detect other types of alcohol besides ethanol, such as methanol, acetone, and the alcohol used in mouthwashes, too.

According to Bactrack, a maker of some types of breathalyzer equipment, there are three different types of breathalyzer devices for DUI offenses.

  • Infrared Spectrometry. This table-top breathalyzer device is what police stations often use. “Spectrometers work by identifying molecules based on the way they absorb infrared light. The level of ethanol in a sample is singled out and measured, and a subject’s alcohol level can then be determined.”
  • Semiconductor oxide-based testers. These are fairly new and used more for home use than for police roadside testing.An ethanol-specific sensor is used to measure the subject’s BAC. Semiconductor sensor technology often involves a tin-oxide material, which is less expensive than platinum fuel cell sensor technology.”
  • Fuel cell testers. About 30 states use these for roadside testing. These devices are also used in substance abuse centers, clinics, and by other entities. “A fuel cell measures alcohol content by creating a chemical reaction that oxidizes the alcohol in the breath sample and produces an electrical current. The more alcohol that is oxidized, the greater the current. The current is measured to determine the subject’s BAC.” Fuel cell sensors are considered the most accurate type of breathalyzer test.

The problem is that breath tests aren’t always reliable when it comes to measuring the amount of alcohol in a bloodstream. The instruments have to be calibrated correctly, and their sensitive nature means that they can be rendered useless if they are not. According to the National Motorists Organization, “Peer reviewed and uncontested studies (LaBianca, Simpson, Thompson prove a margin of error of 50% when comparing breathalyzer estimates of Blood alcohol content to actual Blood alcohol content! That means a breathalyzer reading of .1 % represents a Blood alcohol content level somewhere between .05 % and .15%.”

At Delius & McKenzie, PLLC, our Sevierville DUI defense attorneys fight aggressively to show the police did not have grounds to stop you. We also fight to prove that the validity of the Breathalyzer machines and the way the officers used them should be contested. If the reliability of the machine or the basis for the police stop is uncertain, then the charges may be dismissed, or it may be possible to work out a plea agreement. Our criminal defense lawyers serve Sevierville, Seymour, Gatlinburg, Pigeon Forge, and the surrounding Tennessee locations, and are ready to help you get justice. To schedule a consultation, call (865) 428-8780 or fill our contact form to discuss your case.