In a showdown between the President of the United States and the United States Supreme Court, the Court will prevail. In the U.S. system of government, the Constitution is the ultimate authority. It has been settled law for over 220 years that the Supreme Court has the final say on the law. To be clear, the Supreme Court says what the law is.
Over the course of American history, Presidents have not infrequently butted heads with the Supreme Court. President Andrew Jackson was often at odds with the Court. In the Supreme Court case Worcester v. Georgia, concerning the property rights of the Cherokee Nation, Jackson ignored a Supreme Court decision ruling that the state of Georgia could not seize the lands of the Native American Cherokee Nation. The Cherokee lands were taken. But in that same year, President Jackson embraced the Supreme Court’s authority by issuing a proclamation of the Supreme Court’s ultimate power to decide constitutional questions and emphasizing that its decisions had to be obeyed. Jackson understood that his executive power was stronger when he obeyed the rule of law.
