Opinion of Rav Ovadiah Yosef on yerushah and intestacy
Source
Opinion of the Rambam
Opinion of the Ramban
Other Rishonim, including Ramban, Rashba and Rosh, disagree. They hold that civil laws enacted for good of the general population are recognized by halacha in private transactions. Rama (Ch.M. 68:1) cites this opinion as halacha.
II. Halacha
Rav Ovadiah Yosef, applying strict adherence to the opinion of Shulchan Aruch, writes that the accepted halacha (at least for Sepharadim) is that dina demalchutah dina only applies to tax and other fiscal laws, but not to laws regulating transactions or disputes between private parties. Therefore, halacha does not recognize the legal inheritance rights of a legal heir who is not a yoresh.
The Rashba wrote that uprooting the laws of yerusha by relying on dina demalchutah dina effectively uproots all of the laws of the Torah. If dina demalchutah had priority over the laws of the Torah, he said, then we would have no need for the Mishnah and Talmud; we would simply teach and apply the law of the land in every situation.
III. Litigation in non-Jewish courts
IV. Conclusion
Rav Ovadiah Yosef concludes that it is forbidden for the non-yorshim to appear in secular court to claim a portion of the estate. If the yorshim wish to share the estate with the non-yorshim, they should execute halachic transfers under the supervision of a bet din.