It's not all that unusual for parents to run off with their children in an effort to take custody matters into their own hands. It happens frequently enough that the federal government has passed two acts to address the problem: the Uniform Child Custody and Enforcement Act and the Parental Kidnapping Prevention Act. It you served your ex with custody papers and her response was to flee with your children, the law is clear that no other state can intercede on custody matters.
Uniform Child Custody and Enforcement Act
Forty-nine states have adopted the terms of the UCCJEA. The lone holdout is Massachusetts, but as of 2014, legislation is proposed to adopt the Act there as well. Under the terms of this act, custody orders typically must be made by the state where the children have lived for the past six months. The fact that one parent is still living in the children's home state gives that state jurisdiction even if the other parent takes the children elsewhere. Your ex must establish residency in her new location for six months – with the children – before the court there would have any power to make a ruling regarding them. However, if you file for custody in your children's home state before your ex establishes residency somewhere else, the home state would have to give its consent to transfer jurisdiction.
Other Provisions of the UCCJEA
A parent can also try to establish that she fled the children's home state because of issues of domestic violence. She can try to get a temporary emergency order for custody in the state where she flees, but even if she is successful, the home state would still have the right to issue a permanent custody order. She might allege that your children have a significant connection with the new state or prove that your state is an inconvenient forum because she and the children now live elsewhere. However, your pending custody action trips the provisions of the other federal act, the PKPA, which prevents her from intentionally creating an inconvenient forum by running away.
Parental Kidnapping Prevention Act
The PKPA also establishes the jurisdictional rights of a child's home state. It provides the distinction between his home state and one with which he might have a significant connection, giving first priority to the home state. Between the provisions of the PKPA and the UCCJEA, the only way another state could make orders regarding your kids is if their home state waives its supremacy and allows it.
What Actions You Can Take
While there are laws to help you get your kids back, you have to take action to implement them. You can file a motion with the family court in your state, asking that your ex be ordered to bring your children home so the court there can decide custody. You can then take a copy of the resulting order to the state where your ex is living and register it with the court there. This usually obligates law enforcement to take custody of your children and return them to you. The court in your state can then issue a custody order based on your original filing.
The Court's Custody Decision
All states base custody decisions on the best interests of the children. A common best interests factor is which parent is most likely to promote an ongoing relationship between the children and their other parent. If your ex has fled the state with the kids, it could very well skew the court's custody decision in your favor. In some states, such as California, the judge can limit your ex's visitation to supervised time only, which means another responsible adult must be present to prevent her from taking your children and running with them again.