Eugene Volokh runs a blog discussing legal issues, and has been covering the issue extensively. He raises some valid points about defects in the OK amendment in this entry:
Others have made similar arguments, arguing against any American court consideration of foreign Islamic court rulings, and of Islamic law. I think those arguments are mistaken, and here’s why.Bottom line: there are cases where an American court needs to look at foreign law in order to establish certain facts regarding the case being considered. This does not mean that the US court is making its rulings according to foreign law.Every year, millions of people from other countries legally come to America, whether as citizens, permanent residents, temporary workers, students, tourists, or whatever else.
American law naturally wants to know certain things about them. Are they married? If they were married, are they divorced? Were the supposed adoptive children they’re bringing with them really adopted? How about the property they’re bringing with them — who really owns it? If they go back to their country of origin, and come back claiming that they divorced the spouses that are still living there, are they telling the truth?
The way that American law generally answers these questions is by looking at the law of the foreign country in which the actions initially took place, especially if the parties to those actions were citizens or residents of that country — for instance, the place where the marriage supposedly took place, where the supposed divorce or adoption decree was procured, or where the property was acquired. If the question is whether a marriage contracted in France between two French citizens is valid, you look to whether the law of France was properly complied with in entering into the marriage. If the question is whether two Taiwanese properly divorced in Taiwan, you look at the divorce decree from the Taiwanese court, and if there are questions about its validity or scope you consult Taiwanese law. (If someone goes to Taiwan to divorce his Canadian wife, who has never been to Taiwan, that divorce decree might not be credited, on the theory that the court lacked jurisdiction over the wife. But if someone goes back to Taiwan to divorce his Taiwanese wife, especially one who has no contact with America, American courts would have no trouble viewing that Taiwanese judgment as dispositive of the husband’s marital status when he comes to America again.)
This is not some newfangled international law theory. This is deeply established American law — specifically the body of law called “choice of law” — which has long called for the consideration of foreign law in such situations.