How do Washington laws address polygamous relationships in the context of family law?

Legal Framework Governing Polygamy in Washington State

In the state of Washington, family law is governed by statutes and case law that shape the legal landscape of domestic relations. One area of particular interest is how these laws deal with polygamous relationships. Polygamy, the practice of having more than one spouse at a time, is illegal in all 50 states of the United States, including Washington. The legal stance on polygamy is clear: it is not recognized or permitted under Washington law.

Polygamy and Washington Law

According to RCW 9A.64.020, bigamy, or being married to more than one person at the same time, is a criminal offense in Washington. This statute ensures that marriage remains a union between two individuals, thereby excluding any form of legally recognized polygamous union. Those found guilty of bigamy in Washington could face legal repercussions including fines and imprisonment.

Historically, the United States has been opposed to polygamy since the mid-1800s, with federal legislation like the Morrill Anti-Bigamy Act of 1862 and subsequent acts reinforcing this position. In Washington, this stance has been maintained consistently throughout the state's history.

Impact on Family Law Matters

Family law matters such as divorce, child custody, and property division are predicated on the existence of a legally recognized marriage. In cases where a polygamous relationship exists but is not legally recognized, individuals may find themselves without recourse through traditional family law channels. For instance, partners in a polygamous relationship cannot seek a divorce because their marriage is not acknowledged by the state.

When it comes to children born into polygamous relationships, issues such as paternity, child support, and custody can become complex. The state prioritizes the best interests of the child but must navigate these situations within the confines of its legal framework which does not recognize polygamous unions.

De Facto Relationships and Cohabitation

While polygamous marriages are not recognized legally in Washington, adults are free to live together and engage in personal relationships as they see fit. These relationships may be considered de facto or cohabitational partnerships. However, these do not carry the same legal rights and responsibilities as marriage.

In some instances, individuals in long-term cohabitational relationships may have certain rights similar to those of married couples under what's known as 'common-law' marriage. However, Washington does not recognize common-law marriages that were created within its borders. It only recognizes common-law marriages from other jurisdictions where they are legally established.


Washington law unequivocally prohibits polygamous relationships from receiving legal recognition or protection under family law. While individuals are entitled to personal liberty in their private lives, any attempt to formalize polygamous unions will confront the barrier of established statutes and case law that uphold monogamy as the lawful standard for marriage within the state.