It is the policy of the General Assembly that the cities of this State should have adequate authority to execute the powers, duties, privileges, and immunities conferred upon them by law. To this end, the provisions of this Chapter and of city charters shall be broadly construed and grants of power shall be construed to include any additional and supplementary powers that are reasonably necessary or expedient to carry them into execution and effect: Provided, that the exercise of such additional or supplementary powers shall not be contrary to State or federal law or to the public policy of this State.
N.C. Gen. Stat. § 160A-4