A Supreme Court's ruling and precedents can change over time as the court reassesses and reinterprets the law in light of new social and legal developments. The Supreme Court has the authority to establish new precedents, through their decisions and rulings that set legal principles that must be followed by lower courts. A precedent can change when a new case is brought before the court, and the court reconsiders its previous ruling, or when the court's composition changes and new justices bring new perspectives to the court.
An example of a precedent that changed over time is the "separate but equal" doctrine. This doctrine, established in the 1896 Supreme Court case Plessy v. Ferguson, upheld the constitutionality of state laws requiring racial segregation as long as the separate facilities were equal in quality. However, in the 1954 case of Brown v. Board of Education, the court reversed this precedent and ruled that segregation in public schools was inherently unequal, and therefore unconstitutional.