Marriage has traditionally been defined by Oregon statute as a civil contract entered into by males at least 17 years of age, and females at least 17 years of age, who are otherwise capable and solemnized in accordance with legal requirements.
Same-sex marriage has also been legally recognized in Oregon since May 19, 2014, when a court case ruled that the Equal Protection Clause of the Federal Constitution required the state to allow same-sex marriages. (As you may also recall, a U.S. Supreme Court case in 2015 ruled that same-sex marriage is legal nationwide).
Prior to the recognition of same-sex marriage, Oregon had enacted a domestic partnership law in 2007, which applied only to same-sex couples. Such same-sex domestic partnerships still exist and are still legally recognized in Oregon. They are generally entitled to the same rights and benefits as married couples. However, such domestic partnerships are less common now that marriage is available to same-sex couples.
Unmarried, opposite-sex couples also form various arrangements, which they sometimes refer to as “domestic partnerships.” These are not recognized in Oregon statutes and are not governed by specific rules. Some such “domestic partnerships” are governed by written agreements between the parties, and others are only verbal. Thus, for opposite-sex couples, the term “domestic partnership” is not clearly defined and could mean many things.
The courts in Oregon have held that if opposite-sex couples want to have the rights and obligations of marriage, they must marry. For example, unlike married couples, if one party in an opposite-sex domestic partnership wishes to add the other party to ownership of real property, they must obtain the consent of the mortgage holder before they may transfer the interest in the property. Whether to grant the consent is up to the policies and standards of the mortgage company.
This rule of law has also been applied in regards to health insurance benefits for unmarried co-habitants.
Regarding domestic partnerships from other states, either for opposite-sex or same-sex couples, Oregon statutes do not require that they be recognized in Oregon. Again, the general principle applies that any couple, either opposite-sex or same-sex, now has the right to marry in Oregon, and if they want the rights and obligations of marriage, they must marry.