What legal principle requires lower courts to follow the decisions of higher courts?

The principle that requires lower courts to follow the decisions of higher courts is known as stare decisis. This Latin term translates to "to stand by things decided." It reinforces the idea that once a court has established a legal principle through its ruling, that principle must be adhered to by lower courts in future cases involving similar issues. This not only promotes consistency and predictability in the law but also respects the hierarchical structure of the judiciary, ensuring that established legal standards are upheld and not arbitrarily overturned.

While legal precedent is closely related—referring to the prior decisions that inform or influence a court's ruling—it is stare decisis that specifically mandates that lower courts follow the binding decisions set forth by higher courts. Judicial review, on the other hand, involves the power of courts to assess whether a law is in compliance with the constitution, while the separation of powers is a constitutional principle that distinguishes the different branches of government and their functions.