Res Judicata is a legal principle that prevents a party from re-litigating a case that has already been decided by a competent court. Once a final judgment is made, the same parties cannot bring the same issue or claim before the court again. This principle promotes judicial efficiency and finality in legal disputes. The doctrine of Res Judicata applies to both civil and criminal cases. It ensures that once a matter has been resolved, it cannot be contested again, thereby protecting the integrity of the judicial system and reducing the burden on courts.