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 Washington State, the law permits divorce on a no-fault basis, which means that a spouse cannot allege the other spouse's fault as grounds for the divorce. The only ground for divorce in Washington is the irretrievable breakdown of the marriage, essentially meaning that the marriage is beyond repair and there are irreconcilable differences between the spouses. When it comes to the division of marital or community property, the court does not consider fault. The property is divided in a manner that the court deems just and equitable, which may not necessarily be equal. However, allegations of fault may still play a role in other aspects of the divorce proceedings, such as spousal support and child custody determinations. It's important to note that while fault is not a factor in the division of property, the behavior of the spouses during the marriage could indirectly influence the court's decisions regarding support and custody if such behavior is relevant to the financial needs of one spouse or the best interests of the child.