O.C.G.A. § 1-3-5: Operation of laws generally; retrospective operation.

Laws prescribe only for the future; they cannot impair the obligation of contracts nor, ordinarily, have a retrospective operation. Laws looking only to the remedy or mode of trial may apply to contracts, rights, and offenses entered into, accrued, or committed prior to their passage; but in every case a reasonable time subsequent to the passage of the law should be allowed for the citizen to enforce his contract or to protect his right.