A more thorough explanation:

The Parental Kidnapping Prevention Act (PKPA) is a law that sets national standards for determining jurisdiction in custody disputes that involve parents who live in different states. The law requires states to enforce custody decisions made by courts in other states if those decisions are consistent with the PKPA. If a state's custody law conflicts with the PKPA, the federal law takes precedence.

For example, in the case of Williams v. Williams, the Supreme Court of North Carolina ruled that an Indiana custody decision could not be enforced in North Carolina because the Indiana court did not have jurisdiction over one of the children involved in the case. This ruling shows how the PKPA requires courts to follow specific jurisdictional rules when enforcing custody decisions made in other states.

The PKPA is an important law that helps prevent parental kidnapping and ensures that custody decisions are made in the best interests of the child. By establishing clear jurisdictional rules, the law helps prevent confusion and disputes between parents who live in different states.