Tenn. Code Ann. § 55-8-142: Turning movements - Signal for stop or decrease in speed

(a) No person shall turn a vehicle at an intersection unless the vehicle is in proper position upon the roadway as required in § 55-8-140 , or turn a vehicle to enter a private road or driveway, or otherwise turn a vehicle from a direct course or move right or left upon a roadway, unless and until this movement can be made with reasonable safety. No person shall so turn any vehicle without giving an appropriate signal in the manner provided in §§ 55-8-143 and 55-8-144 in the event any other traffic may be affected by this movement.

(b) No person shall stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided herein to the driver of any vehicle immediately to the rear when there is opportunity to give this signal.