Chemical Tests — How They Work in Georgia DUI Cases

You may be wondering how a chemical test of your blood, breath, or urine factors into a DUI case.

In most situations, chemical tests are collected for forensic purposes — meaning they are intended to produce scientific evidence that the prosecutor can use in court. Specifically, the results are often used to support a DUI per se charge by attempting to prove your blood alcohol concentration (BAC) was at or above the legal limit of 0.08%.

A breath test is typically administered at the police station by an officer who is certified to operate the testing machine. The result generated by that machine is what the State relies on to argue impairment “per se” — based strictly on the number.

A blood test, on the other hand, is drawn by a nurse, phlebotomist, or other qualified medical professional. The sample is then sent to the Georgia Bureau of Investigation’s Division of Forensic Science. There, a forensic toxicologist analyzes the sample and prepares an official report showing the alleged blood alcohol concentration. That report is provided to the prosecutor and may be used as evidence in court.

If the reported result is at or above the legal limit, the State will attempt to use it to prove a DUI per se charge. In those situations, the accuracy, reliability, and admissibility of that chemical test become critical issues — and they must be carefully examined and, when appropriate, challenged in court.