Chemical breath tests, BAC and DUI in Alabama

On Behalf of | Nov 9, 2023 | Criminal Defense, DUI |

You have probably heard that 0.08% is considered the legal limit for DUI in Alabama. This term “legal limit” is somewhat misleading and leads many people to misunderstand their rights. In this blog post, we will attempt to briefly explain what this percentage figure means and why it is important in any DUI case.

Blood alcohol concentration

The percentage figure refers to the amount of alcohol in a driver’s bloodstream. This is known as blood alcohol concentration, or BAC.

Under Alabama law, it is a crime for any person to drive a motor vehicle if their BAC is 0.08% or higher. For drivers under age 21, the BAC level is just 0.02%.

Police have several means of determining a driver’s BAC. The most common method they use is to administer a chemical breath test at the roadside, using a portable handheld device. The driver blows into the device, and the device supposedly measures their BAC.

Chemical breath tests are not always reliable. In some cases, the devices themselves are not properly prepared. In others, the administering officer is not properly trained in using the device.

Police officers know this, and so they often try to back up a suspect’s breath test results with more accurate data. For this, they may transport the suspect to a facility where trained personnel can administer a blood or urine test. However, police are not always able to do this, and so many DUI prosecutions rely heavily on the evidence of breath test results.

Defending against breath test evidence

At first glance, breath test evidence can seem very strong and scientific, but those who are facing DUI charges can defend against it. They can point out the unreliability of the results and question whether the arresting officer used the device correctly.

We should note here that chemical breath test results usually aren’t the only evidence prosecutors present at trial. They may also have the results of a field sobriety test (such as when officers have a driver try to walk a straight line) and other notes or testimony from the officer or witnesses who were present at the scene. However, when a defendant can cast doubt on BAC test results, they can go a long way toward defeating the prosecution’s case against them.