The shared image that most in Roswell have in reference to drunk driving it likely that of a person outside his or her car blowing into a handheld device under the supervision of a law enforcement officer. Despite measuring one's breath, the actual reading being sought is the alcohol content in one's blood. This might immediately prompt the question of how can a breath measurement say anything abouit your blood? Furthermore, how accurate is such a measurement, and should it be viewed as the sole factor when determining if you are guilty of driving under the influence?
You ingest ethanol alcohol when you drink. That ethanol eventually makes its way to your bloodstream before taking a long journey around your body and eventually ending up in your lungs, where it is vaporized into a gas and escapes your body when you breathe. According to The Alcohol Pharmacology Education Partnership, using your breath to measure your BAC requires assuming that the alcohol content in air you breathe is directly proportional that which is in your blood (yet not equal). A conversion factor is needed for authorities to understand what you BAC based of the alcohol content of your breath.
The standard conversion used for breath tests measuring BAC is 2100:1 (1 mL of blood having 2100 times the alcohol concentration of 1 mL of your breath). This conversion factor is actually an average of measurements obtained different samples measured using different devices. Experts have pointed out that the blood-to-breath ratio can vary between 1500:1 to 3000:1. Thus, it is recognized that the BAC obtained from a breath test could likely by over- or under-reporting your true BAC. Your knowledge that this potential discrepancy exists could support your challenge of any breath test submitted against you as evidence in you DUI case.