The United States Court of Appeals for the Ninth Circuit is the U.S. federal court of appeals that has appellate jurisdiction over the U.S. district courts in the following federal judicial districts:District of Alaska District of Arizona Central District of California Eastern District of California Northern District of California Southern District of California District of Hawaii District of Idaho District of Montana District of Nevada District of Oregon Eastern District of Washington Western District of Washington

The Pioneer Courthouse is a federal courthouse in Portland, Oregon, United States. Built beginning in 1869, the structure is the oldest federal building in the Pacific Northwest, and the second-oldest west of the Mississippi River. Along with Pioneer Courthouse Square, it serves as the center of downtown Portland. It is also known as the Pioneer Post Office because a popular downtown Portland post office was, until 2005, located inside. The courthouse is one of four primary locations where the United States Court of Appeals for the Ninth Circuit hears oral arguments. It also houses the chambers of the Portland-based judges on the Ninth Circuit.