Tenn. Code Ann. § 67-4-2801

The purpose of this part is to levy a tax on every merchant of unauthorized substances to generate revenue for state and local law enforcement agencies for use by those agencies to investigate, combat, prevent and reduce drug crimes, and for the general fund. Such tax shall be measured by the quantity of unauthorized substances sold, bartered, traded, or distributed to another for consideration or the quantity of unauthorized substances possessed with intent to sell, barter, trade, or distribute to another for consideration. This is not a criminal statute. It is a civil taxing measure contributing to the general revenue fund and a civil remedial measure designed to mitigate against the enormous costs of law enforcement related to drug control for state and local government. Nothing in this part may in any manner provide immunity from criminal prosecution for a person who possesses an illegal substance.