The nation’s largest federal appeals court gets a new presiding officer Monday as Sidney Thomas, an appointee of President Bill Clinton, succeeds Alex Kozinski as chief judge of the Ninth U.S. Circuit Court of Appeals in San Francisco. While continuing to hear judicial cases, the chief judge also acts as the court’s administrator and heads policy-making bodies for the circuit, which includes federal courts in California and eight other Western states. The chief judge also has a vote on some of the court’s most contested cases, in which a majority of the 29-judge court votes to rehear a three-judge panel’s decision before an 11-judge “en banc” tribunal. Kozinski, while generally conservative on criminal law, is also a libertarian who has sided with some of the court’s more liberal judges on issues such as gay rights.