Legal certainty and the orderly development of legal principles are promoted by the application of the doctrine of "stare decisis", also known as the doctrine of binding precedent. According to this doctrine, the decisions of higher courts are binding on lower courts. Thus, judgments of the Court of Appeal are binding on the High Court, and judgments of both of these superior courts are binding on subordinate courts. A judge is generally not bound by previous decisions made by other judges in courts of the same level. Thus, a judge hearing a High Court case need not follow previous High Court decisions. Nonetheless, courts generally do so as a matter of comity, unless there are good reasons for doing otherwise. As the final appellate court in Singapore, the Court of Appeal is not bound by its previous decisions or those of predecessor courts such as the Privy Council. However, the Court continues to treat such decisions as "normally binding" and only departs from them "where adherence to such prior decisions would cause injustice in a particular case or constrain the development of the law in conformity with the circumstances of Singapore". Only the "ratio decidendi" (that is, the legal principle that determines the outcome) of a case is binding according to the doctrine of "stare decisis"; other legal principles expressed that are not crucial to the final decision ("obiter dicta") are only persuasive.