The United States Supreme Court is the highest court in the land, and one of its main duties is to decide the outcome of cases. As the Supreme Court is the highest court, all decisions and outcomes are final and a case that goes to the Supreme Court must first pass through many other courts. The Supreme Court has the power to investigate, question and overturn cases that were decided in lower courts.
The Supreme Court can also judge the actions of federal, state and local governments. If the Supreme Court feels that another area of government is acting unconstitutionally, they may investigate. Due to the powers of separation in the U.S. government, however, the Supreme Court does not have the ability to act completely on its own. The members of the Supreme Court are appointed by the president but must be approved by Congress. While the Supreme Court has the power to judge laws of Congress, it requires congressional approval in order to function.