Where divorce recognizes that the spouses were once married, Oregon annulments terminate a marriage retroactively; they vacate the marriage.

The Oregon law on annulment is in ORS 106.020. 106.030. 106.050. 107.005, and 107.015.

Oregon courts vacate two kinds of invalid marriages: void marriages and voidable marriages. Void marriages are immediately invalid, and are never considered marriages by the court; voidable marriages can exist until the court grants the annulment. For example, bigamous or incestuous marriages are void. Annulments can end voidable marriages, such as a marriage that took place when either party was too young or otherwise incapable of granting consent. The grounds for annulments of voidable marriages can be waived by living together after the condition is discovered or cured.

Courts grant annulments when specific grounds exist, and they can be granted only so long as these conditions exist. So, for example, if a marriage is based upon the fraud or deception by one spouse, an annulment can be granted when the other spouse learns of it. If that spouse learns of the fraud but remains in the marriage, the marriage can no longer be annulled because the ground for annulment no longer exists. After that, the couple must divorce.

Void marriages include:

Voidable marriages include:

Under certain circumstances, a marriage may be annulled due to the way it was performed or witnessed.

To file for an annulment in Oregon, the marriage must have happened there or at least one spouse must live in Oregon for at least six months before filing.

The petitioner must establish grounds for an annulment. The clerk of the county court provides the appropriate annulment papers. The petitioner files packet one packet if there are no minor children and a different one if minor children are involved. The forms are completed in duplicate; one copy goes to the spouse, the other stays with the petitioner.

All documents, except the summons, are filed with the county clerk. The petitioner must sign up for a parenting class if there are minor children.

The sheriff, professional process server, or a friend who is at least 18, serves the respondent with the annulment papers. Someone other than the petitioner must serve the spouse. A missing spouse may be served by an alternative means of service, such as service by publication. Failing to issue a response results in a default judgment in favor of the petitioner. The court will not issue a judgment default if the other spouse files a response.