An excerpt from the Community Education booklet Family Law in Oregon
What is annulment?
Annulment is a way of legally ending, or canceling, a marriage. You can get an annulment only in unusual cases. For example, you can annul your marriage if one of the spouses is already married or not old enough to legally marry. You cannot get an annulment just because your marriage is only a few days old or because you have not had sex with your spouse.
A lawyer can help you find out if you can get an annulment. Court costs for an annulment are about the same as for a divorce.
Can I get an annulment in Oregon if I was married in a state other than Oregon?
You can get an annulment for a non-Oregon marriage if your situation fits the rules for annulment and you or your spouse have been living in Oregon for at least six months.
If my spouse was already married to someone else when we got married, do I need a court order to end my marriage?
In most cases, if you were married in Oregon to someone who was already married, then your marriage is void (does not exist). You do not need an annulment unless there are children to support, property to be divided, or you want a court document for your records. If you were married outside Oregon to someone who was already legally married, it will take a court order to end the marriage.
If you were married in Oregon before July 31, 1981, to someone who was already married, you may need a divorce to end the marriage. Contact a lawyer.