42 U.S.C. 3604 prohibits discrimination in the sale or rental of housing and makes it unlawful to refuse to sell, rent, or negotiate for the sale or rental of a dwelling based on a protected class. Protected classes at a federal law level are – race, color, religion, national origin, sex, familial status, and disability. The Pregnancy Discrimination Act of 1978 expanded the definition of “discrimination on a basis of sex” to include discrimination due to pregnancy, childbirth, or related medical conditions. HUD issued a memorandum in February of 2021 that indicated that discrimination on a basis of sex also included discrimination due to gender identity and sexual orientation, largely based on the combination of Executive Order 13988 and Bostock v. Clayton County, Georgia. Disability was added in the Rehabilitation Act of 1973. Under ORS 659A.421, Oregon has a similar law prohibiting discrimination in sale and rental of real estate, and the state expressly adds sexual orientation, gender identity, marital status, and source of income to the list of protected classes. Some local governments have added other classes to the protected class list as well: for example, Eugene prohibits discrimination based on ethnicity, Corvallis prohibits discrimination based on religious observance, and several cities and Wasco county prohibit discrimination on a basis of domestic partnership.
Discrimination at law is defined as “different treatment for similarly situated parties, particularly where no legitimate reason exists.” There are many instances where a decision may be discriminatory, but not a violation of fair housing laws. For example, a seller refuses to sell to their mother-in-law. The Seller is objectively treating a similarly situated party differently, and arguably not doing so for a legitimate reason. However discriminatory it may be on a literal level, refusing to sell to a mother-in-law is not a fair housing violation [unless the seller is refusing to sell to the mother-in-law as a result of her religion or race, etc.].
Advertisements by brokers tend to be one of the primary regions where fair housing violations occur. Whenever advertising, think critically about the words you use, it may be wise to consult HUD’s guidance: https://www.hud.gov/sites/documents/DOC_7784.PDF. Remember though – HUD is not the only authority, and your state and local governments may have additional protections in place for certain groups.