Project: Whose Laws Reign Supreme? The Supreme Court and Federal Law The Supreme Court of the United States is the final legal authority in the nation. The Supreme Court can overturn decisions made in other courts, as the jurisdiction of the Supreme Court is the most powerful. This means that the Supreme Court can overturn federal laws if they are found to be unconstitutional. In order to do this, the Supreme Court must find that the law in some way violates the laws and procedures established by the Constitution. This is a wonderful example of how the system of checks and balances is designed to operate.