SDCL § 32-26-22.1: Stopping or slowing signal required--Improper use of signals--Violation as misdemeanor.

No person may stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided in § 32-26-23 to the driver of any vehicle immediately to the rear when there is opportunity to give such signal. The signal provided in § 32-26-23 shall be used to indicate an intention to turn, change lanes, or stop 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. A violation of this section is a Class 2 misdemeanor.