RCW 66.28.130: Selling, supplying, or serving of liquor to or consumption by standing or walking person.

It shall not be unlawful for a retail licensee whose premises are open to the general public to sell, supply, or serve liquor to a person for consumption on the licensed retail premises if said person is standing or walking, nor shall it be unlawful for such licensee to permit any said person so standing or walking to consume liquor on such premises: PROVIDED HOWEVER, That the retail licensee of such a premises may, at his or her discretion, promulgate a house rule that no person shall be served nor allowed to consume liquor unless said person is seated.