O.C.G.A. § 15-19-7: Proof of authority.

The presiding judge or justice, on motion of either party and on showing reasonable grounds therefor, may require any attorney who assumes the right to appear in a case to produce or prove the authority under which he appears and to disclose, whenever pertinent to any issue, the name of the person who employed him and may grant any order that justice may require on such investigation. However, prima facie, attorneys shall be held authorized to represent properly any case in which they may appear.