Once a lawsuit is filed, there is a period of discovery in which the parties exchange evidence and take depositions. In almost every case, there is tension in regard to what must be disclosed to the other side. Georgia law says that parties may obtain discovery regarding any matter, not privileged, which is relevant to the subject matter involved in the pending action, whether it relates to the claim or defense of the party seeking discovery. It is not grounds for objection that the information sought will be inadmissible at the trial if the information sought appears reasonably calculated to lead to the discovery of admissible evidence.
What does this mean? Well, it means that most anything that is or may become an issue in the litigation must be disclosed. The same rationale applies to discovery to a third-party (i.e., a party that is not named in the lawsuit). The way this is applied, as a practical matter, is that the court will look at issue in dispute and decide whether the information or documents sought are relevant or likely to lead to the discovery of admissible evidence. This is a liberal standard but there must be some connection between the evidence sought and a dispute in the lawsuit.