Tenn. Code Ann. § 39-11-112

When a penal statute or penal legislative act of the state is repealed or amended by a subsequent legislative act, the offense, as defined by the statute or act being repealed or amended, committed while the statute or act was in full force and effect shall be prosecuted under the act or statute in effect at the time of the commission of the offense. Except as provided under § 40-35-117, in the event the subsequent act provides for a lesser penalty, any punishment imposed shall be in accordance with the subsequent act.