In North Carolina under G.S. 20-154(a) a driver “before starting, stopping or turning from a direct line shall first see that such movement can be made safely…and whenever the operation of any other vehicle may be affected by such movement, shall give a signal as required.” So basically a driver does not have to give a turn signal unless it would affect another vehicle that is following. Also a driver is not required to give a turn signal if he is in a lane where the turn is not optional, for example a right turn only lane. The reasoning is that a vehicle who is following should know that a vehicle in that lane will be making a turn. This was the rule that came from State v. Ivey, 360 N.C. 562 (2006) where the defendant was in the right turn only lane.
In State v. Styles, by contrast the court found that signal was required. The defendant changed lanes directly in front of another vehicle in that case. The court said that changing lanes immediately in front of another vehicle could affect the operation of the following vehicle. However in State v. Watkins, 725 S.E.2d 400 (2012) it was found that where the defendant did not have to signal while changing lanes because he was three to four car lengths in front of the vehicle that was following him so it is not clear that another vehicle was affected.State v. Styles, 362 N.C. 412 (2008)