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 Massachusetts, spouses seeking a divorce can file on either fault or no-fault grounds. No-fault divorce is based on an 'irretrievable breakdown' of the marriage, and it does not require spouses to prove wrongdoing by the other party. This can be done through a joint petition with a separation agreement (1A divorce) or through a unilateral filing by one spouse (1B divorce). On the other hand, Massachusetts also allows for fault-based divorces, where one spouse alleges specific grounds for the breakdown of the marriage. The fault grounds recognized by Massachusetts include adultery, desertion, gross and confirmed habits of intoxication, cruel and abusive treatment, non-support, impotency, and a prison sentence of five years or more. While fault grounds can be alleged, they are less commonly pursued due to the complexity and additional proof required. In terms of property division, Massachusetts is an equitable distribution state, meaning the court will divide marital property in a manner it deems fair, though not necessarily equal. While fault is not a primary factor in property division, it can be considered by the court alongside other factors to achieve an equitable result. Additionally, fault may play a role in determinations of alimony and child custody.