Section 22111 Of Chapter 6. Turning And Stopping And Turningsignals From California Vehicle Code >> Division 11. >> Chapter 6.

. All required signals given by hand and arm shall be given from the left side of a vehicle in the following manner:
  (a) Left turn--hand and arm extended horizontally beyond the side of the vehicle.
  (b) Right turn--hand and arm extended upward beyond the side of the vehicle, except that a bicyclist may extend the right hand and arm horizontally to the right side of the bicycle.
  (c) Stop or sudden decrease of speed signal--hand and arm extended downward beyond the side of the vehicle.