Seattle has made illegal the practice of landlords checking the criminal history of prospective tenants, with only narrow exceptions.
Seattle residential landlords are required to provide written notice that the landlord is prohibited from requiring the disclosure, asking about, rejecting an applicant, or taking adverse action based on any arrest record, conviction record, or criminal history.
There is a narrow exception for registered sex offenders. However, even for registered sex offenders the landlord must have a “legitimate business reason” to deny renting to the prospective tenant, and then give notice of the adverse action and the rationale for the legitimate business reason. If the offense that gave rise to the sex offender registration was committed while the registrant was a juvenile, a landlord may not use the registration as a basis for denying rental to the prospective tenant.
There is also an exception for landlords who live in the property, but rent our portions of it.
Tenants and occupants may complain to the City, which will conduct an investigation. The City has the power to compel discovery, including interrogatories and oral depositions. Landlords found in violation may face penalties of up to $55,000.
 Seattle Municipal Code Chapter 14.09 (Fair Chance Housing).