STARE DECISIS - Lat. "to stand by that which is decided." The principal that the precedent decisions are to be followed by the courts.
To abide or adhere to decided cases. It is a general maxim that when a point has been settled by decision, it forms a precedent which is not afterwards to be departed from. The doctrine of stare decisis is not always to be relied upon, for the courts find it necessary to overrule cases which have been hastily decided, or contrary to principle. Many hundreds of such overruled cases may be found in the American and English books of reports.
...
Although the doctrine of stare decisis does not prevent reexamining and, if need be, overruling prior decisions,
"It is . . . a fundamental jurisprudential policy that prior applicable precedent usually must be followed even though the case, if considered anew, might be decided differently by the current justices. This policy . . . 'is based on the assumption that certainty, predictability and stability in the law are the major objectives of the legal system; i.e., that parties should be able to regulate their conduct and enter into relationships with reasonable assurance of the governing rules of law.'" (Moradi-Shalal v. Fireman's Fund Ins. Companies (1988) 46 Cal.3d 287, 296.)
Accordingly, a party urging overruling a precedent faces a rightly onerous task, the difficulty of which is roughly proportional to a number of factors, including the age of the precedent, the nature and extent of public and private reliance on it, and its consistency or inconsistency with other related rules of law.
http://www.lectlaw.com/def2/s065.htm
