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 Oklahoma, both bigamy and polygamy are illegal. Under Oklahoma law, bigamy is considered a felony. Specifically, according to Oklahoma Statutes Title 21, Section 881, it is unlawful for a person who is married to marry another person or cohabit with another person. This applies to individuals who have a spouse living, from whom no valid divorce has been obtained. This means that marrying another person while still legally married to someone else is a criminal offense. Additionally, Oklahoma does not recognize polygamous marriages for any purpose. As such, any marriage license obtained while already married is invalid, and engaging in polygamy can lead to criminal charges.