Title 40, Chapter 6, Section 123
(a) No person shall turn a vehicle at an intersection unless the vehicle is in proper position upon the roadway as required in Code Section 40-6-120 or turn a vehicle to enter a private road or driveway or otherwise turn a vehicle from a direct course or change lanes or move right or left upon a roadway unless and until such movement can be made with reasonable safety. No person shall so turn any vehicle without giving an appropriate and timely signal in the manner provided in this Code section.
(b) A signal of intention to turn right or left or change lanes when
required shall be given continuously for a time sufficient to alert
the driver of a vehicle proceeding from the rear in the same
direction or a driver of a vehicle approaching from the opposite
(c) No person shall stop or suddenly decrease the speed of a vehicle
without first giving an appropriate signal in the manner provided in
this Code section to the driver of any vehicle immediately to the
rear when there is an opportunity to give such signal.
(d) The signals provided for in subsection (b) of Code Section 40-6-124 shall be used to indicate an intention to turn, change lanes, or start from a parked position and shall not be flashed on one side only on a parked or disabled vehicle or flashed as a courtesy or "do pass" signal to operators of other vehicles approaching from the rear.