Tennessee DUI Law Terms
While the correct abbreviation in for Driving Under the Influence under Tennessee DUI law is “DUI,” this offense is also commonly referred to as Driving While Intoxicated (DWI), Drunk Driving, Operating Under the Influence (OUI), Operating While Intoxicated (OWI), and Impaired Driving. Driving Under the Influence (DUI) is not only a serious crime under Tennessee DUI laws, carrying harsh penalties for offenders, but DUI cases are also among the most complex in our judicial system. One reason DUI cases are so complex is the many constitutional law issues relating to illegal searches and seizures, which so often are encountered in drunk driving investigations. Another reason is the advanced science involved in the chemical (usually blood or breath) testing associated with DUI cases.
Understanding the Crime of Tennessee Driving Under the Influence
Both the Tennessee Constitution and the Constitution of the United States afford citizens a presumption of innocence—in other words you cannot be found guilty of DUI or any other crime unless the State of Tennessee, also known as the prosecution, proves that you are guilty of a crime beyond a reasonable doubt. To be found guilty of Driving Under the Influence, Tennessee DUI laws require the prosecution to establish beyond a reasonable doubt that the person was: (1) operating or in physical control of (2) a motor vehicle on (3) any public road, highway, alley, parking lot, or any other premises generally frequented by the public while (4) under the influence of alcohol or drugs (illicit or prescription drugs), or with a blood alcohol content of .08% or higher.
How Does an Officer Determine “Under the Influence?”
DUI is one of the few crimes for which a person can be convicted solely upon the opinion of a police officer. Officers are trained to evaluate certain criteria when determining whether to arrest an individual for Driving Under the Influence. Factors considered by police officers in Tennessee and across the country include:
- Driving behaviors, including a motorist’s reaction to the officer’s emergency equipment;
- Driver’s ability to divide attention once stopped (e.g. answer questions while providing driver’s license, proof of insurance and proof of vehicle registration);
- Driver’s physical demeanor, including speech (slurred?), eyes (bloodshot?), ability to walk (staggered?), odor (strong odor of alcoholic beverage on breath?), etc.; and
- Driver’s ability to perform field sobriety tests.
How is Blood Alcohol Content (BAC) measured?
The Blood Alcohol Content (BAC) of a person accused of Driving Under the Influence in Tennessee may be determined by a blood test, breath test, or urine test. These tests are also commonly referred to as “chemical tests.” Tennessee DUI laws allow the arresting officer to choose which test to administer. Accordingly, a Tennessee motorist cannot demand one form of test over another (e.g. breath test rather than a blood test).
Many people who submit to a chemical test and register above the Tennessee legal limit for alcohol (.08% for Driving Under the Influence, .04% for Commercial Motor Vehicle DUI, and .02% for Underage Driving While Impaired), often believe that their case cannot be successfully defended and choose not to retain a Tennessee DUI lawyer. However, an investigation of a case by a Tennessee DUI attorney often reveals evidence that can call into doubt the reliability of a blood, breath or urine test and may even result in keeping the test results from being introduced in court.