SAN FRANCISCO » One of the nation’s largest federal appeals courts has a new chief judge.

Sidney Thomas took over as chief judge of the 9th U.S. Circuit Court of Appeals this month from Judge Alex Kozinski. The appeals court’s judges convened in a special session Friday for a ceremony to mark the change in court leadership.

The most senior active judge under the age of 65 is eligible to serve as chief judge for a term of up to seven years. Kozinski’s seven-year term ended in December. The 61-year-old Thomas, of Billings, Montana, will take over various administrative duties as chief judge.

The Ninth Circuit hears cases from Alaska, Arizona, California, Hawaii, Idaho, Montana, Nevada, Oregon, Washington, the U.S. Territory of Guam and the Commonwealth of the Northern Mariana Islands.