The United States Court of Appeals for the Ninth Circuit (in case citations, 9th Cir.)

[1] Headquartered in San Francisco, California, the Ninth Circuit is by far the largest of the 13 U.S. Courts of Appeals, covering a total of nine states and two territories and with 29 active judgeships.

Ninth Circuit judges are also appointed by the United States secretary of the interior to serve as temporary acting Associate Justices for non-federal appellate sessions at the High Court of American Samoa in Fagatogo.

Congress never created a federal district court in the Philippines from which the Ninth Circuit could hear appeals.

The cultural and political jurisdiction of the Ninth Circuit is just as varied as the land within its geographical borders.

[10][11] However, a detailed study in 2018 reported by Brian T. Fitzpatrick, a law professor at Vanderbilt University, looked at how often a federal circuit court was reversed for every thousand cases it terminated on the merits between 1994 and 2015.

"[15] Chief among these is the Ninth Circuit's unique rules concerning the composition of an en banc court.

By contrast, in the Ninth Circuit it is impractical for 29 or more judges to take part in a single oral argument and deliberate on a decision en masse.

The result, according to detractors, is a high risk of intracircuit conflicts of law where different groupings of judges end up delivering contradictory opinions.

[18] In March 2007, Associate Justices Anthony Kennedy and Clarence Thomas testified before a House Appropriations subcommittee that the consensus among the justices of the Supreme Court of the United States was that the Ninth Circuit was too large and unwieldy and should be split.

[19] Congressional officials, legislative commissions, and interest groups have all submitted proposals to divide the Ninth Circuit such as: The more recent proposals have aimed to redefine the Ninth Circuit to cover California, Hawaii, Guam, and the Northern Mariana Islands, and to create a new Twelfth Circuit to cover Alaska, Arizona, Idaho, Montana, Nevada, Oregon, and Washington.