In child custody disputes in which the parents and children have significant contacts with more than one state—such as having homes in multiple states and spending significant amounts of time in multiple states—there may be a question of which state’s courts have jurisdiction over the child custody dispute (the authority to hear and decide the dispute). The Uniform Child Custody Jurisdiction Enforcement Act (UCCJEA) is a law adopted by most states (all but Massachusetts) that determines which state’s courts have jurisdiction to hear and decide a child custody dispute in such a situation.

In Montana, as in most other states, the Uniform Child Custody Jurisdiction Enforcement Act (UCCJEA) governs jurisdiction in child custody disputes involving multiple states. The UCCJEA is designed to determine which state has the authority to decide a child custody matter when the child and parents have significant connections with more than one state. Under the UCCJEA, the child's 'home state'—defined as the state where the child has lived with a parent or a person acting as a parent for at least six consecutive months immediately before the commencement of the child custody proceeding—generally has jurisdiction. If the child is less than six months old, the home state is where the child has lived since birth. The Act also provides for circumstances where the home state declines jurisdiction because it is an inconvenient forum or if no state qualifies as the home state. In cases where the child is present in Montana and it is necessary to protect the child from threats of harm, Montana courts may exercise temporary emergency jurisdiction. The UCCJEA also includes provisions for enforcing child custody determinations made by courts in other states that comply with the Act's jurisdictional standards.