(a) Offense. - A person commits the offense of impaired driving if he drives any vehicle upon any highway, any street, or any public vehicular area within this State:
(1) While under the influence of an impairing substance; or
(2) After having consumed sufficient alcohol that he has, at any relevant time after the driving, an alcohol concentration of 0.08 or more. The results of a chemical analysis shall be deemed sufficient evidence to prove a person's alcohol concentration; or
(3) With any amount of a Schedule I controlled substance, as listed in G.S. 90-89, or its metabolites in his blood or urine.
(a1) A person who has submitted to a chemical analysis of a blood sample, pursuant to G.S. 20-139.1(d), may use the result in rebuttal as evidence that the person did not have, at a relevant time after driving, an alcohol concentration of 0.08 or more.
(b) Defense Precluded. - The fact that a person charged with violating this section is or has been legally entitled to use alcohol or a drug is not a defense to a charge under this section.
(b1) Defense Allowed. - Nothing in this section shall preclude a person from asserting that a chemical analysis result is inadmissible pursuant to G.S. 20-139.1(b2).
(c) Pleading. - In any prosecution for impaired driving, the pleading is sufficient if it states the time and place of the alleged offense in the usual form and charges that the defendant drove a vehicle on a highway or public vehicular area while subject to an impairing substance.
(d) Sentencing Hearing and Punishment. - Impaired driving as defined in this section is a misdemeanor. Upon conviction of a defendant of impaired driving, the presiding judge shall hold a sentencing hearing and impose punishment in accordance with G.S. 20-179.
(e) Exception. - Notwithstanding the definition of "vehicle" pursuant to G.S. 20-4.01(49), for purposes of this section the word "vehicle" does not include a horse.