A DUI under Tennessee law can be accomplished in one of two ways. Either if your blood alcohol level is .08 or higher at the time of driving, or if your ability to operate a motor vehicle was impaired by alcohol and you lacked clearness of mind. It is very simple. You can be convicted under two theories of DUI - blood alcohol, or how your driving was impaired, affecting whether or not you were able to operate the vehicle safely. In Tennessee, a DUI can only be a felony if it is your 4th offense. Normally what the government does is look back through your record and see if you have any prior DUI arrests. The more you get, the worse it gets. For a 2nd DUI offense is a greater punishment, a 3rd is more punishment and a 4th is a felony. A felony DUI carries 1-6 years in prison and carries a minimum of 150 days in jail. It gets progressively worse with the more you get, but for most folks, a DUI is not a felony.