The county courthouse, located in Friday Harbor, is listed on the National Register of Historical Places. The courthouse currently houses the offices of the Auditor, Treasurer, Assessor, Board of County Commissioners, District Court, Superior Court, Prosecutor, Juvenile Court Services and the Sheriff. The Sheriff's Office provides armed security throughout this building and in particular, for all courtroom hearings and trials.

RCW 9.41.300 prohibits any type of weapon in the building and everyone is subject to a search of person and belongings when visiting the courthouse.