Georgia Code Title 9. Civil Practice § 9-4-7

(a) No declaration shall prejudice the rights of persons not parties to the proceeding.

(b) In any proceeding involving the validity of a municipal ordinance or franchise, the municipality shall be made a party and shall be entitled to be heard as a party.

(c) If an Act of the General Assembly, a statute of the state, any order or regulation of any administrative body of the state, or any franchise granted by the state is alleged in an action for declaratory judgment or as a part of any other action to be unconstitutional or otherwise invalid, the Attorney General of the state shall be served with a copy of the proceeding and shall be entitled to be heard in defense of said Act, statute, order, regulation, or franchise, which may include appearing as a party as of right as he or she determines is appropriate.