(a) Except as provided in subsection (b) of this Code section, the authority granted to municipalities by this article shall not apply to:

(1) A municipality whose charter does not authorize a municipal court;

(2) A municipality whose charter provides for the election, as judge or judges and not as members of the municipal governing authority, of the judge or judges of a court having jurisdiction over municipal ordinance violations; or

(3) A municipality whose charter expressly provides that the municipality shall not have the authority granted by this article.

(b) The authority granted to municipalities by this article shall, notwithstanding the provisions of subsection (a) of this Code section, apply to any municipality if as of June 30, 1983, jurisdiction over violation of its ordinances was by law vested in a magistrate court in existence on that date.