(a) Any juvenile, including a juvenile who is under the jurisdiction of the court, who commits a criminal offense on or after the juvenile has reached the age of 18 years is subject to prosecution as an adult. A juvenile who is emancipated shall be prosecuted as an adult for the commission of a criminal offense.
(b) A juvenile shall be prosecuted as an adult for any criminal offense the juvenile commits after a district or superior court conviction if either of the following applies:
(1) The juvenile has previously been transferred to and convicted in superior court.
(2) The juvenile has previously been convicted in either district or superior court for a felony or a misdemeanor. Violations of the motor vehicle laws punishable as a misdemeanor or infraction shall not be considered a conviction for the purposes of this subsection unless the conviction is for an offense involving impaired driving as defined by G.S. 20-4.01(24a).