Under the Hague Convention on the Civil Aspects of International Child Abduction when a Country has political subdivisions, such as California in the the United States of America, when reference is made to a child having habitual residence in California, it includes habitual residence in the larger political structure.

When lawyers are filing divorce or custody papers in a court, they usually will determine a  state of habitual residence for the child, so that there is a “home court” for jurisdiction of the child.

Article 31

In relation to a State which in matters of custody of children has two or more systems of law applicable in different territorial units –

a) any reference to habitual residence in that State shall be construed as referring to habitual residence in a territorial unit of that State;

b) any reference to the law of the State of habitual residence shall be construed as referring to the law of the territorial unit in that State where the child habitually resides.