Article 4
If the spouses, before marriage, have not designated the applicable law, their matrimonial property regime is governed by the internal law of the State in which both spouses establish their first habitual residence after marriage. Nonetheless, in the following cases, the matrimonial property regime is governed by the internal law of the State of the common nationality of the spouses - 1. where the declaration provided for in Article 5 has been made by that State and its application to the spouses is not excluded by the provisions of the second paragraph of that Article; 2. where that State is not a Party to the Convention and according to the rules of private international law of that State its internal law is applicable, and the spouses establish their first habitual residence after marriage -
a. in a State which has made the declaration provided for in Article 5, or b. in a State which is not a Party to the Convention and whose rules of private international law also provide for the application of the law of their nationality;
3. where the spouses do not establish their first habitual residence after marriage in the same State. If the spouses do not have their habitual residence in the same State, nor have a common nationality, their matrimonial property regime is governed by the internal law of the State with which, taking all circumstances into account, it is most closely connected.