Most states allow spouses seeking a divorce to allege fault in the breakup of the marriage as a basis for the divorce. Alleging the other spouse’s fault—rather than seeking the divorce on no-fault grounds (irreconcilable differences or incompatibility, making the marriage unsustainable)—is generally a basis for requesting the court make an uneven distribution of the marital or community property in favor of the spouse alleging the other’s spouse’s fault.

In states that allow a spouse to seek a divorce on fault grounds, the grounds that may be alleged vary from state to state, but generally include adultery, cruelty, conviction of a felony, family or domestic violence, abandonment, mental illness, and substance abuse (drugs and alcohol). Spouses may also seek a divorce on no-fault grounds in these states.

In no-fault states, a spouse is not allowed to allege fault as grounds for the divorce, and the court is not allowed to consider fault in dividing the marital or community property—but allegations of fault may be considered for other purposes, such as spousal support and child custody. No-fault states include California, Colorado, Florida, Hawaii, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, Oregon, Washington, and Wisconsin. And in some states “incurable insanity” is a no-fault ground for divorce.

The grounds on which a spouse may seek a divorce (fault or no-fault) are usually located in a state’s statutes—often in the family code or domestic relations code.

In Oregon, a no-fault divorce state, a spouse cannot allege fault as grounds for the divorce. The state's divorce laws require that the dissolution of marriage be based on 'irreconcilable differences' that have caused the irreparable breakdown of the marriage. This means that the court will not consider fault when dividing marital or community property. However, allegations of fault may still play a role in other aspects of the divorce proceedings, such as spousal support and child custody determinations. Oregon's approach to divorce is designed to avoid the need for spouses to prove wrongdoing by the other party, which can simplify the process and reduce conflict. The relevant statutes can be found in the Oregon Revised Statutes, specifically under the family law or domestic relations sections.