What is stare decisis? It is an American legal principle which comes from the royal courts of England. It assumes a highly hierarchical court organization. The higher in the hierarchy a court is, the larger the scope of its prior decision’s authority is.
What does stare decisis do? The principle of stare decisis ensures that past judicial decisions are formally “binding” on factually similar present controversies within the same jurisdiction (a kind of geographical limitation). In other words, when a court has established a principle of law as applicable to a certain state of facts, that court and lower courts will follow that principle in all future cases in which the facts are substantially the same. Thus, the principles of stare decisis gives precedential value to past court decisions within well-established geographical and factual limits.
For example, a decision of the Supreme Judicial Court of Massachusetts is a precedent and so generally binding in future “like” cases in that court and the other “lower” Massachusetts courts, such as the “intermediary court” named the “Massachusetts Appeals Court,” but it is not binding on any future cases arising in the courts of Georgia or California or some other state.
U.S. Supreme Court decisions are not binding upon state court decisions, unless the state decisions regard a legal federal question. A federal question is an issue that regards the interpretation of a federal statute, federal regulation, or of the Constitution of the United States. A state’s highest court has the last word on issues of that state’s law.