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 Alaska, spouses seeking a divorce can file on either fault or no-fault grounds. No-fault divorce is based on an 'incompatibility of temperament' which has made it impossible for the spouses to live together. This is similar to the 'irreconcilable differences' ground found in other states. For fault-based divorces, Alaska law recognizes several grounds including adultery, cruelty, personal indignities rendering life burdensome, habitual gross drunkenness, drug addiction, conviction of a felony, desertion for a period of one year, and mental illness requiring confinement for 18 months. While Alaska is not strictly a no-fault state, the court does not necessarily need to consider fault when dividing marital property. However, fault may be a factor in the division of property if it is relevant to the acquisition or destruction of marital assets. Additionally, fault can be considered when determining issues such as spousal support and child custody.