<P> The Chief Justice of the United States is the chief judge of the Supreme Court of the United States and thus the head of the United States federal court system, which functions as the judicial branch of the nation's federal government . The Chief Justice is one of nine Supreme Court justices; the other eight have the title Associate Justice . </P> <P> The Chief Justice, as the highest judicial officer in the country, serves as a spokesperson for the federal government's judicial branch, and acts as a chief administrative officer for the federal courts . The Chief Justice is also head of the Judicial Conference of the United States, and in that capacity appoints the director of the Administrative Office of the United States Courts . By law, the Chief Justice is also a member of the Board of Regents of the Smithsonian Institution, and by custom is elected chancellor of the board . </P> <P> The Chief Justice leads the business of the Supreme Court and presides over oral arguments . When the court renders an opinion, the Chief Justice--when in the majority--decides who writes the court's opinion . The Chief Justice also has significant agenda - setting power over the court's meetings . In the case of an impeachment of a President of the United States, which has occurred twice, the Chief Justice presides over the trial in the U.S. Senate . Additionally, the presidential oath of office is typically administered by the Chief Justice (although the Constitution does not assign this duty to anyone in particular). </P> <P> Since the Supreme Court was established in 1789, 17 persons have served as chief justice . The first was John Jay (1789--1795). The current chief justice is John Roberts (since 2005). Four--Edward Douglass White, Charles Evans Hughes, Harlan Fiske Stone, and William Rehnquist--were previously confirmed for associate justice and subsequently confirmed for chief justice separately . </P>

What us supreme court justice presides over presidential impeachment proceedings