Under what conditions can a state that did not enter the original custody order modify it?

A state that did not enter the original custody order can modify it under specific conditions prescribed by the Uniform Child Custody Jurisdiction and Enforcement Act (UCCJEA). One key condition is when the court that originally has jurisdiction no longer exists or refuses to exercise its jurisdiction. This means that if the original court is unavailable to modify custody—due to factors like closure, dissolution, or a refusal to hear the case—the new state may assume jurisdiction and make modifications in the best interest of the child.

This situation ensures that the child's welfare remains the priority, and provides a mechanism for resolution when the initial court is incapacitated. Other choices may seem viable but do not meet the legal requirements set forth under UCCJEA. For example, mutual agreement of both parents or the child reaching the age of 18 does not automatically grant a state the authority to modify a custody order, as these factors do not inherently establish jurisdictional power to change the terms of custody.