When a marriage breaks down, it is not uncommon for one parent to wish to return, with his or her children, to their state of origin. This is usually without the permission of the other parent. This becomes an international child abduction. The United Nations Convention on the Rights of the Child requires "State Parties shall take measures to combat the illicit transfer and non-return of children abroad". Also that they "promote the conclusion of bilateral or multilateral agreements or accession to existing agreements". International child abductions are a matter treated by civil law and in some cases criminal law.