” If it is between 2 frum Jewish parties, Beis Din will rule based exclusively on Halacha, not goyish law. Dinei Momunos are binding, and not secular law, if in conflict (i.e. Halacha demands one ruling while goyish law demands the opposite ruling.) “
This is actually a complicated issue. A few years ago a beit din ruled in favor of a teacher who had been dismissed from a yeshiva, forcing the yeshiva to grant the teacher tenure. An out of control judge (who was reported by some to be a member of the Orthodox community!) overturned the beit din’s decision, saying it was irrational and contrary to public policy. Fortuntately the judge was overturned on appeal but it IS true that in the US, religious courts are subject to secular courts. There is actually a serious proposal in Texas that would essentially ban religious courts from using religious law in making decisions; I’m surprised that the Jewish community is not fighting it tooth and nail.