You can compel a witness to appear in court by serving a subpoena on that person. Generally, you can obtain a subpoena from the Clerk of Court. There is a County-specific charge for a subpoena. The witness must be served with the subpoena at least twenty-four (24) hours before the time scheduled for their appearance.
Subpoenas shall be issued, signed and sealed, in blank to a party who shall fill in the name and address of the witness and file it with the clerk at least six hours before appearance is required. The party subpoenaing a witness must pay the witness a fee.
If the witness must come from another county, the witness is also entitled to receive reimbursement for a roundtrip mileage from their home or residence to the courthouse. See O.C.G.A. § 24-10-24 for fees and mileage rates.