Erroneous DUI (driving under the influence) results can get you convicted even if you weren't intoxicated at the time of your arrest. Knowing why DUI tests sometimes go wrong can help you defend yourself against DUI charges. Below are some of the causes of erroneous DUI test results.
Storage, Handling, or Contamination Issues
Improper storage and handling of test samples can lead to contamination that can affect the accuracy of the results. Contamination from chemicals or substances that contain alcohol, such as paint, are especially dangerous. Say the storage container is not as airtight as it should be, and it is stored in the vicinity of other substances (maybe evidence in other criminal cases); the eventual test result can easily read a higher BAC than you actually had at the time of the arrest.
Improper Calibration of Equipment
There are various forms of DUI tests, and some of them use equipment that needs to be calibrated to give accurate results. The breathalyzer is a classic example of such a test. The breathalyzer, which you blow into to determine the amount of alcohol in your breath, can give the wrong results if it is improperly calibrated. The longer the breathalyzer has been in use, and the more people that have used it, the higher the likelihood is that it needs to be calibrated.
Mouth-System Alcohol Discrepancy
The breathalyzer test measures the amount of alcohol in your mouth, which is not always the same as the amount of alcohol in your bloodstream. For example, the level of alcohol in your breath may be high if you have just taken a sip of alcohol, vomited, or burped. Unfortunately, it is the amount of alcohol in your bloodstream that gives an indication of the level of your intoxication.
The police are supposed to wait for a few minutes if they suspect that the level of alcohol in your mouth is higher than the level of alcohol in your system. Without such a waiting period, the breathalyzer result will not be a true reflection of your level of intoxication.
In a few cases, an existing medical condition can amplify the level of alcohol in your system and lead to an erroneous test result. That might be the case, for example, if you have a medical condition that triggers heartburn or acid reflux, which increases the level of alcohol vapor in your breath.
Proving a DUI test result as wrong is not easy. You will probably need an expert witness to help you. Contact a DUI attorney for help with your particular case.