The U. S. District Court for the Western District of Washington serves as the federal trial court for the portion of the State of Washington west of the Cascade Mountain range and from the Oregon border to the Canadian border. The eastern part of the state is served by the U. S. District Court for the Eastern District of Washington. Cases from the Western District of Washington are appealed to the United States Court of Appeals for the Ninth Circuit.

Seattle Division: Island, King, San Juan, Skagit, Snohomish and Whatcom counties
Tacoma Division: Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Kitsap, Lewis, Mason, Pacific, Pierce, Skamania, Thurston and Wahkiakum counties