The Supreme Court:
Most cases do not start in the Supreme Court. Usually, cases are first brought in front of lower (state or federal) courts. If a case starts at the local level and the losing party does not think that justice was served with that court's decision, the party may appeal the case or bring it to a higher court. If the higher court agrees with the lower court, the party may then ask that the case be taken to the Supreme Court. Only cases involving federal or Constitutional law are brought to the highest court in the land.
Though not often exercised, original jurisdiction gives the Court the power to sit as a trial court to hear cases affecting ambassadors and other foreign officials, and in cases in which a state is a party. Only disputes between two or more states must be heard initially in the Supreme Court. The 1997-98 dispute between New York and New Jersey over the ownership of Ellis Island is an example of the Supreme Court exercising original jurisdiction.
Approximately 7,500 cases are sent to the Supreme Court each year. Out of these, only about 80 to 100 are actually heard by the Supreme Court. Why so few? Well, when a case arrives to be heard by the Supreme Court, several things happen. First, the Justices get together to decide whether the case is worthy of being brought before the Court. In other words, does the case really involve federal or Constitutional law? Secondly, a Supreme Court ruling can affect the outcome of hundreds or even thousands of cases in lower courts around the country. Therefore, the Court tries to use this enormous power only when a case presents a pressing constitutional issue.