North Carolina General Statutes Chapter 160A. Cities and Towns § 160A-174. General ordinance-making power

(1) The ordinance infringes a liberty guaranteed to the people by the State or federal Constitution;

(2) The ordinance makes unlawful an act, omission or condition which is expressly made lawful by State or federal law;

(3) The ordinance makes lawful an act, omission, or condition which is expressly made unlawful by State or federal law;

(4) The ordinance purports to regulate a subject that cities are expressly forbidden to regulate by State or federal law;

(5) The ordinance purports to regulate a field for which a State or federal statute clearly shows a legislative intent to provide a complete and integrated regulatory scheme to the exclusion of local regulation;

(6) The elements of an offense defined by a city ordinance are identical to the elements of an offense defined by State or federal law.