One question I am asked is why does it take so long for the blood alcohol test take so long to be tested. Here is the answer. Most of the blood alcohol samples are tested by the Tennessee Bureau of Investigation (TBI). The TBI has three labs for 95 Tennessee counties. Once the blood specimen is drawn, it is the local law enforcement agency to get the sample to the TBI. It could spend days or weeks at the police department. It is usually taken to a drop box outside the lab.
Once it is received by the TBI, a lab tech checks the sample in, assigns it a lab number, and places in a refrigerated locker. The sample sits in the locker until a lab person checks the sample out to their work station. A sample is prepared. It is then run through a machine called a headspace gas chromatography. Here is a link to a short video By Dr.Harold McNair. As a small footnote, I had the opportunity to attend a weeklong class on gas chromatography where Dr. McNair was one of the instructors. The machine tests the blood and it produces a result. The lab person does nothing more than sign their name to the computer-generated report.
The report is then sent to the law enforcement officer that conducted the test. It takes weeks to get the result back.
What happens if the test is negative for alcohol to the blood alcohol level is below the legal limit of .08. The sample is retested for the presence of drugs in your blood. Add weeks to that time frame.
Another factor in the length of time in getting a blood sample result is the increased use of blood tests in DUI prosecutions. In the last several years, police routinely obtain a search warrant to get a blood alcohol sample even if the driver refuses to consent.
Defending DUI cases are becoming more difficult in Middle Tennessee. Not impossible. It requires more hard work other than just saying my client has never been in trouble before.
