Q Why should not “Dina Demalchuta Dina” apply to all wills, and therefore become valid according to Jewish Law?
A. Some contemporary Poskim indeed maintain that secular wills are Halachically valid based on the principle of dino demalchuso dino, which translates as the law of the kingdom governs This obligation applies mainly in civil law, and not in matters of ritual law.
Igros Moshe, (E.H. 1: 104) mentions: “that although we are dealing with a gift to be made after the death of the donor, and there is no such thing as a gift after death, as the object no longer belongs to the donor and such a gift is therefore not valid in Jewish law, nevertheless, according to the law of the land a person can legally transfer with effect after death money or any other object which at that time obviously no longer belongs to him or her … but in essence it is clear, according to my humble opinion, that a testament of this kind, the dispositions of which will certainly be put into effect by the authorities of the country, does not need a kinyan as one could not imagine a more effective kinyan than this. Hence, since a kinyan is not necessary, the beneficiaries can uphold their right also against those persons who are the proper heirs by Torah law.”
Achiezer (3: 34) also sponsors the principle of dino demalchuso since it makes the receiver a muchzak.
However, a number of Poskim disagree, and follow the opinion of the Remah, that it does not apply in monetary conflicts between two Jewish individuals, for if it would then all the monetary laws of the Torah would become void (Remah C.M. 9: 11, 253: 32) Pischei Choshen H. Yerusha 4: 34).
Binyan Ariel (p. 170), Minchas Yitzchok (6: 164) and other Poskim advise to make a proper tzavaah or testament following Halacha, but at the same time also write a legally executed will, that supports the tzavaah.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a