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 when it comes to the division of marital or community property. The state only requires that one spouse assert that the marriage has suffered 'irreconcilable differences' that have led to the 'irremediable breakdown' of the marriage. This means that issues such as adultery, cruelty, abandonment, or substance abuse are not considered by the court when dividing property. However, such allegations of fault may be relevant in other aspects of the divorce proceedings, such as determining spousal support or child custody. Oregon's approach aims to avoid the often contentious and invasive process of proving fault, thereby simplifying the divorce process and focusing on equitable solutions without assigning blame.