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 Oregon, 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, health, or behavior of the child or either parent. The petition to modify custody is typically filed in the same court where the original divorce and custody determination was made. 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 court that has jurisdiction over the child's new residence. Oregon law requires that the court consider the best interests of the child when deciding whether to grant a modification of custody. The process involves submitting a formal request to the court and potentially attending a hearing where both parents can present their case for why the custody order should or should not be changed.