The appointment of the Chief Justice of the United States is an infrequent event of majorsignificance in American politics. The appointment of each Justice to the Supreme Court issignificant because of the enormous judicial power that the Court exercises as the highest appellatecourt in the federal judiciary. The Chief Justice, like each of the Court's other eight Justices, castsone vote when the Court rules on cases. However, the Chief Justice also exercises a leadership roleand wields unique influence, both within the Court itself and in the federal judiciary as a whole. Chief Justice appointments occur infrequently, with only 16 individuals having served in thatposition since 1789 -- an average tenure of 13Â½ years per Chief Justice. (1) On September 3, 2005, Chief Justice William H. Rehnquist died, after having served almost19 years as Chief Justice. (2) He had been diagnosed with cancer in October 2004 and, although in ill health since then, hadmanaged to lead the Court through its last term, which ended in late June 2005. His death cameabout two months after Associate Justice Sandra Day O'Connor had announced her intention to retirefrom the Court, (3) and onlya few days before the scheduled start of confirmation hearings, on September 6, 2005, for hernominated successor, John G. Roberts, Jr., a U.S. appellate court judge. On September 6, PresidentGeorge W. Bush withdrew the Roberts nomination for the O'Connor seat and instead nominatedJudge Roberts for Chief Justice. (4) At age 50, Judge Roberts, if confirmed by the Senate, wouldbecome the youngest Chief Justice at time of confirmation in more than 200 years. (5) Out of respect for the lateChief Justice, whose funeral was held on September 7, the Senate Judiciary committee postponedthe start of its hearings on Judge Roberts' nomination to be Chief Justice until September 12. Following four days of hearings on the nomination, the Judiciary Committee on September 22approved Judge Roberts to be Chief Justice by a 13-5 vote. That action sent the nomination to thefull Senate, which is expected to vote on whether to confirm Judge Roberts on September 29. Any Supreme Court nomination must be confirmed by the U.S. Senate, which, in recentCongresses, has been embroiled in controversies over various of the President's nominations to thelower federal courts. At times, Senate Democrats have accused President Bush of using hisnominating power to appoint to the courts persons having controversial ideological agendas, and ofmaking judicial appointments during Senate recesses in order to bypass the need for Senateconfirmation. (6) SenateRepublicans, in turn, have accused Senate Democrats of using their own ideological "litmus tests"to oppose certain judicial nominees and of making improper use of filibusters (extended debate asa delaying tactic) on the Senate floor to block Senate votes on circuit court nominees whom theyoppose. (7) Against this backdrop, a Supreme Court vacancy can be seen by Senators of both parties, atleast to some extent, in an ideological context. Many highly controversial decisions of the Court inrecent years have been closely decided, by 5-4 votes, appearing to underscore a longstandingphilosophical or ideological divide in the Court between its more "liberal" and "conservative"members. Depending on their judicial philosophy, future appointees to the Court, Senatorsrecognize, could have a potentially decisive impact on the Court's ideological balance and, as well,on whether past rulings of the Court will be upheld, modified, or overturned. (8) All other things being equal, the appointment of a Chief Justice, owing to the responsibilitiesof the office and its symbolic importance, is foremost among the appointments that a Presidentmakes to the Supreme Court. Under any circumstances, it will command the attention of Congress,especially the Senate, which votes on whether to confirm judicial nominations. Even more attentionis expected in the current political environment, in light of the controversy that has recentlysurrounded the judicial appointment process and the importance that the President and Senators ofboth parties have attached to upcoming Supreme Court appointments. Other factors, moreover, can further complicate the appointment of a Chief Justice. Theprocess, for instance, might become more contentious if the appointment of a new Chief Justice wereseen as affecting the ideological balance of the Court, and thus galvanize opposition from Senatorsunhappy with the implications of the appointment. The process also might become morecomplicated if another Supreme Court appointment needs to be made at or around the same time asthe Chief Justice appointment. This situation can arise, for instance, if a President nominates anAssociate Justice to be Chief Justice, or if (as happened recently) an Associate Justice stepped downat about the same time as a Chief Justice vacancy were created -- in either case, creating an AssociateJustice vacancy for the President to fill. This report is intended to help show what is unique about the office and to shed light on theprocess by which a Chief Justice is appointed. Hence, an initial section reviews the vast range ofduties and responsibilities of the Chief Justice and the qualifications considered necessary for oneto perform effectively in that office. A second section then examines the Supreme Courtappointment process, focusing on the appointment of Chief Justices. At the end of this report, atable lists the names of all persons nominated for Chief Justice, from 1789 to the present, includingtheir nomination dates and, if confirmed by the Senate, the dates of their confirmation, judicial oath,and end of service, as well as their ages at time of appointment and upon termination of service. For a more detailed review of each stage in the Supreme Court appointment process, as itapplies to Associate Justice as well as Chief Justice nominees, see CRS Report RL31989 , SupremeCourt Appointment Process: Roles of the President, Judiciary Committee, and Senate . Only one of the Chief Justice's responsibilities is specified in the Constitution. Article I,Section 3, Clause 6 states that the Chief Justice shall serve as the presiding officer of the Senateduring an impeachment trial of the President. Otherwise the Constitution does not mention the ChiefJustice. The Judiciary Act of 1789, one of the first laws enacted by the first Congress, stipulatedthat the Supreme Court would consist of a Chief Justice and five Associate Justices. (9) In the two centuries thatfollowed, Congress enacted legislation authorizing certain powers to the Chief Justice, and otherduties have evolved over time through custom and practice. The Chief Justice is the Court's most highly visible and identifiable figure -- by virtue of theposition's prominence and prestige, and the powers it has acquired by statute or through custom. TheChief Justice has been called the "first among equals" on the nine-member Court. Each Chief Justicebrings an individual style of leadership that influences the way the Court operates, deliberates, andconducts its work. Moreover, the Chief Justice has considerable influence on the interactions thatoccur among the Justices. Many Chief Justices have left an indelible mark on the Court throughtheir vision and leadership. Some, in retrospect, are admired for their constitutional scholarship,others are noted for their acumen in working effectively with the other Justices and the legislativeand executive branches, and still others are recognized for administrative and organizationalskills. (10) The Chief Justice's most prominent role is that of presiding officer of the Court. In thiscapacity, the Chief Justice: presides at the private conference during which the Court decides which lowercourt decisions to accept from the large number received on appeal; presides over the public sessions, or hearings of cases, that come before theCourt; chairs the private conference at which cases are discussed among the ninemembers of the Court and eventually decided by a vote of the Justices; and assigns, when in the majority, the writing of the Court's opinion on the caseeither to himself or to one of the Associate Justices. (11) The Chief Justice is also manager of the Supreme Court's building and the overall operationsof the Court. The administrative duties attendant to this role have increased over the years,commensurate with the growth of the nation, the sheer volume of cases presented to the Court,technological advances in court operations, and current security requirements. (12) Managerial tasks includeapproving the appointment of some court employees and the rules of the Supreme Court Library. The Chief Justice, too, is the head of the federal judicial branch of government. In thiscapacity, key statutory duties of the Chief Justice include chairmanship of the Judicial Conferenceof the United States, (13) overall supervision of the Administrative Office of the United States Courts, (14) and chairmanship of theBoard of the Federal Judicial Center. (15) Other duties include appointing two members of the Judiciaryto the Commission on Executive, Legislative and Judicial Salaries; reporting to Congress on changesin the Federal Rules of Criminal Procedure prescribed by the Supreme Court; (16) and, under the ForeignIntelligence Surveillance Act, appointing 11 federal judges to the Foreign Intelligence SurveillanceCourt. (17) As the head of the judicial branch, the Chief Justice is its spokesman and advocate. In thiscapacity, the late Chief Justice, William H. Rehnquist, took a leadership role in pressing for increasesin judicial salaries and in funding for judicial branch operations. In his 2004 Year-End Report onthe Federal Judiciary , for instance, Chief Justice Rehnquist underscored his concern about the"funding crisis currently affecting the federal judiciary." (18) The tradition of the Chief Justice writing an annual report on thefederal judiciary was begun by Chief Justice Warren E. Burger in 1970. (19) The Chief Justice has statutory authority and responsibilities related to the circuit courts. Bythe order of the Supreme Court, the Chief Justice and the Associate Justices are allotted as circuitjustices among the circuits.