When you have decided to end your marriage and file for a divorce, there are various "grounds" upon which to file. State laws vary somewhat regarding the different grounds for a divorce, but all states differentiate between "no-fault" divorces, and situations in which one person is alleged to be at fault. "No-fault" means that neither party is to blame for the divorce, and involuntary separation is one type of reason for a "no-fault" for divorce. In at-fault divorces, state laws dictate various reasons considered valid grounds for a divorce.

While state laws vary, involuntary separation essentially is based on the couple having lived apart for a consecutive period. Laws in different jurisdictions vary as to the minimum length of involuntary separation required for a divorce to occur. Maryland, for example, stipulates a minimum of 24 months, while in the District of Columbia, only one year of involuntary separation is required. The person filing for the divorce must prove to the court that the couple have not lived together and have not had sexual relations for the number of months stipulated by state law as a requirement for divorce to be granted on grounds of involuntary separation.

In a divorce based on involuntary separation, there is no need for either party to prove that the other was at fault. In this respect, a divorce based on involuntary separation may be less emotionally fraught than a contested divorce in which fault must be proven. In addition, one party does not need the other's consent in order to start divorce proceedings. If the couple have been living separately for the state-required minimum separation period, one party can file for divorce without the other party's agreement.

One situation in which involuntary separation can be used as grounds for a divorce is if a spouse is incarcerated for a period longer than the state-required minimum separation period. If one party wanted to file for divorce from an incarcerated spouse on grounds of involuntary separation, it would be necessary to prove that no conjugal visits occurred during the spouse's incarceration.

When a spouse in the military is deployed abroad or at sea for an extended period of time that equals or exceeds the minimum requirement of a particular state's divorce law, this is considered to constitute involuntary separation. Therefore, military deployment can be used as grounds for a no-fault divorce.