Controlled Substances - As introduced, decriminalizes the possession of less than one ounce of marijuana or less than five marijuana plants; authorizes municipalities and counties to impose civil penalties on the possession of marijuana in certain circumstances. - Amends TCA Title 16, Chapter 18, Part 3; Title 39, Chapter 17, Part 4 and Title 40.

SB 923 decriminalizes the possession of less than one ounce (28.35 grams) of marijuana or up to five marijuana plants in Tennessee, removing criminal penalties for these amounts. It directly affects individuals caught with these small quantities, while allowing municipalities and counties to impose civil penalties (up to $250) for public possession or casual sharing of small amounts. Key provisions include defining "casual exchange" as spontaneous sharing without money or payment methods, and specifying penalties calculated at $25 per 0.1 ounce or $50 per plant. The bill does not change laws regarding marijuana sales or larger quantities, and takes effect July 1, 2025.