Bigamy is the act of marrying one person while being legally married to another. Polygamy is the practice or custom (often religious) of having more than one wife or husband at a time. Most states prohibit a party from having more than one marriage license at a time, and in most states bigamy is a crime.
In Washington State, bigamy is illegal under RCW 9A.64.010, which defines bigamy as the act of knowingly contracting or purporting to contract a marriage with another person while having a living spouse, or cohabitating with another person under the appearance of being married. Bigamy is classified as a felony offense in Washington. Polygamy, which involves having more than one spouse simultaneously, is not legally recognized and is encompassed under the prohibition against bigamy. Therefore, both bigamy and polygamy are against the law in Washington State, and individuals engaging in such practices may face legal penalties.