Wash. Rev. Code § 16.50.100
The legislature of the state of Washington finds that the use of humane methods in the slaughter of livestock prevents needless suffering; results in safer and better working conditions for persons engaged in the slaughtering industry; brings about improvement of products and economy in slaughtering operations; and produces other benefits for producers, processors and consumers which tend to expedite the orderly flow of livestock and their products. It is therefore declared to be the policy of the state of Washington to require that the slaughter of all livestock, and the handling of livestock in connection with slaughter, shall be carried out only by humane methods and to provide that methods of slaughter shall conform generally to those authorized by the Federal Humane Slaughter Act of 1958, and regulations thereunder.
RCW 16.50.100