Wash. Admin. Code § 162-36 § 162-36-005

(1) It is an unfair practice for any person, whether acting for himself, herself, or another, because of sex, sexual orientation, gender expression or gender identity, marital status, race, creed, color, national origin, families with children status, the presence of any sensory, mental, or physical disability, or the use of a trained dog guide or service animal by a disabled person:
(a) To refuse to engage in a real estate transaction with a person;
(b) To discriminate against a person in the terms, conditions, or privileges or a real estate transaction or in the furnishing of facilities or services in connection therewith;
(c) To refuse to receive or to fail to transmit a bona fide offer to engage in a real estate transaction from a person;
(d) To refuse to negotiate for a real estate transaction with a person;
(e) To represent to a person that real property is not available for inspection, sale, rental, or lease when in fact it is so available, or to fail to bring a property listing to his or her attention, or to refuse to permit the person to inspect real property;
(f) To discriminate in the sale or rental, or to otherwise make unavailable or deny a dwelling, to any person; or to a person residing in or intending to reside in that dwelling after it is sold, rented, or made available; or to any person associated with the person buying or renting;
(g) To make, print, publish, circulate, post, mail, or cause to be so made or published a statement, advertisement, or sign, or to use a form of application for a real estate transaction, or to make a record or inquiry in connection with a prospective real estate transaction, which indicates, directly or indirectly, an intent to make a limitation, specification, or discrimination with respect thereto;
(h) To offer, solicit, accept, use, or retain listing of real property with the understanding that a person may be discriminated against in a real estate transaction or in the furnishing of facilities or services in connection therewith;
(i) To expel a person from occupancy of real property;
(j) To discriminate in the course of negotiating, executing, or financing a real estate transaction whether by mortgage, deed of trust, contract, or other instrument imposing a lien or other security in real property, or in negotiating or executing any item or service related thereto including issuance of title insurance, mortgage insurance, loan guarantee, or other aspect of the transaction. Nothing in this section shall limit the effect of RCW 49.60.176 relating to unfair practices in credit transactions;
(k) To attempt to do any of the unfair practices defined in this chapter or chapter 49.60 RCW.
(2) It is an unfair practice for any person, for profit, to induce or attempt to induce any person to sell or rent any real property by representations regarding the entry or prospective entry into the neighborhood of a person or persons of a particular race, creed, color, sex, sexual orientation, gender expression or gender identity, national origin, families with children status, or with any sensory, mental or physical disability and/or the use of a trained dog guide or service animal by a disabled person.
(3) It is an unfair practice to insert in a written instrument relating to real property a provision that is void under RCW 49.60.224 (1) or to honor or attempt to honor such a provision in the chain of title.
(4) Nothing in this chapter prohibits a person engaged in the business of furnishing appraisals of real property to take into consideration factors other than race, color, creed, national origin, sex, sexual orientation, gender expression or gender identity, disability, the use of a trained dog guide or service animal by a disabled person, or families with children status.
(5) Nothing in this chapter limits the applicability of any reasonable federal, state or local restrictions regarding the maximum number of occupants permitted to occupy a dwelling.
(6) Nothing in this chapter prohibiting discrimination based on families with children status applies to housing for older persons as defined by the federal Fair Housing Amendments Act of 1988, 42 U.S.C. Sec. 3607 (b)(1) through (3), as amended by the Housing for Older Persons Act of 1995, P.L. 104-76, as enacted on December 28, 1995.