Compelling the Lower Courts
The law-of-the-case doctrine holds that the decision of the reviewing court in a case remains the law of that case on the questions of law.
This includes all subsequent proceedings at the trial and appellate levels. The doctrine functions to compel trial courts to follow the mandates of reviewing courts.
Assume Retrospective Application of Law
There is an essential rule governing the application of changes in the law to a case. Any intervening decision by the Supreme Court is to be applied retroactively unless the Supreme Court specially decrees that the change in the law has only prospective application.
It’s axiomatic that an earlier decision is not considered to be bad law. Rather, it must be treated as though it never was the law.