While the Constitution establishes the Supreme Court, it does not set its size or methods of operation. Since 1869, the Court has had one chief justice and eight associate justices. Until then, Congress changed the size of the court to suit its political needs. Under the Constitution, the Supreme Court has original jurisdiction in cases involving foreign ambassadors and cases in which a state is one of the parties. There have been only 150 cases since 1789 which have fallen into either of these categories. The Supreme Court's major function has become trying cases on appeal. On average, 5,000 cases are appealed to the Court annually, 95 percent of which are denied writs of certiorari. A writ of certiorari is issued if four justices vote to take the case under advisement.