In Oklahoma, it’s illegal to drive with a blood alcohol concentration (BAC) above .08. Besides field sobriety tests, the most common way police officers will determine a person’s BAC is with a breathalyzer. Breathalyzers are more convenient and less invasive than blood tests, but they are also less accurate. In fact, preliminary breath tests conducted by a police officer before an arrest are not admissible in Oklahoma due to their inaccuracy.

Breathalyzers, or preliminary breath tests, that are conducted when a driver is pulled over generally use semiconductor sensor technology, which is more inexpensive but less accurate. These sensors can be thrown off by environmental factors, like the smell of acetone or cigarette smoke. Sometimes things like mouthwash or medications can make it look like a person has alcohol in their system, even if that is not the case. Despite these inaccuracies, breathalyzers give police probable cause to make an arrest.

Even breathalyzer machines that are considered to be more reliable, like ones that use fuel cell sensors, can still produce false positives. Breathalyzers can also show inaccurate readings and lead to an improper DUI charge if they are not regularly calibrated. Defense attorneys can request calibration logs from prosecutors in discovery to check whether the breathalyzer was adequately calibrated.

When a high-grade breathalyzer is used, the results can still be called into question if there is any sign of human error or if the breathalyzer is shown to have a history of inconsistency. Thus, even if a breathalyzer result is unfavorable, individuals should always remember that they do not have to answer an officer’s questions, such as ones about the number of drinks they had or what they were drinking. It may be wise to speak with a criminal defense attorney before making a statement to authorities.