Either parent may file a petition to modify a child custody order—but usually only when there is a substantial change in circumstances that affects the child (including changes in one or both of the parents’ lives) that justifies the court revisiting and possibly modifying the earlier child custody order.

The petition to modify child custody generally must be filed in the same court in which the parents’ divorce case was decided. But if the child lives in a different county or state, the courts of the county or state where the child lives may be the proper place to file a petition to modify a child custody order.

In Utah, either parent has the right to petition the court to modify a child custody order. This can be done if there is a substantial change in circumstances that affects the welfare of the child, such as changes in the living situation, financial status, or health of either parent, or the needs of the child. The petition to modify custody should generally be filed in the same court where the original divorce and custody determination took place. However, if the child has since moved and now resides in a different county or state, the petition may need to be filed in the jurisdiction where the child currently lives. This is in accordance with the Uniform Child Custody Jurisdiction and Enforcement Act (UCCJEA), which Utah has adopted, and which dictates that the child's home state has jurisdiction over custody matters. It's important to note that the court will always prioritize the best interests of the child when considering any modifications to custody arrangements.