Chapter 8: What Are The Different Types Of DUI In Tennessee? Per Se, Impairment, And By Consent

There are two different ways that the State can seek to prove the crime of DUI in Tennessee, either: (1) per se; or (2) by impairment.

The first way that the State will attempt to prove a DUI is through proving that the defendant’s blood or breath alcohol concentration in their blood at the time of driving was more than .08%. Unlike in some other states, the blood alcohol level is on its own crime, rather than simply being a way to prove impairment by alcohol. This means that even someone who is not “impaired,” but does have a .08% blood-alcohol concentration, is guilty of DUI. The State usually seeks to prove a .08% blood-alcohol concentration either by a forensic breath test or forensic blood test. How those tests work and the defenses to them are covered in the next chapter.

The second way that the State often seeks to prove DUI, especially when no breath or blood test was administered, is by showing that the defendant was impaired to such a degree that they were not able to safely operate a motor vehicle. Whether the person was impaired is ultimately a question for the jury, but the State often seeks to prove impairment through a combination of a police officers’ observations, defendants’ words and admissions, the defendants’ actions and demeanor, performance on field sobriety test, and other physical and mental indicators of impairment such as slurred speech, bloodshot, red, and watery eyes, unsteadiness on one’s feet, and the inability to concentrate and/or carry-on a conversation.

Lastly, a rare case, but one that may occur nonetheless, that many people do not know about is that you can be prosecuted for the crime of DUI if the State can prove that you aided and abetted another in the commission of a DUI. This type of charge is often called DUI by consent or DUI by proxy. Under DUI by consent, the State can prosecute someone for DUI if they can prove that they aided and abetted, or should be held criminally responsible for the conduct of another. For example, the passenger of the vehicle who is also the owner of the vehicle that allowed an impaired person to drive their car may be charged with DUI. In this circumstance, the State would need to prove additionally that the person charged with DUI by consent had actual knowledge that the driver was too impaired to drive the vehicle but that the defendant allowed the individual to drive anyways.