Jews are forbidden to charge each other interest on loans, so if a contract calls for interest, a Beth Din will often strike that provision. Jewish law considers many payments that allow one to pay more but pay later to fall under this prohibition, so even things that do not seem like interest may be included. Jewish law allows a workaround called a heter iska, which restructures a transaction with interest into a different kind of transaction with mostly similar effects, but if the parties do not enter into a heter iska, interest is generally unenforceable.
Every seven years, at the end of a shmittah year, loans between Jews are nullified, unless the creditor executed a document called a pruzbul after the loan was made but before the nullification. The nullification takes place immediately before Rosh Hashana following the shmittah year. The next such nullification will take place in 2022. There are several exceptions even without a pruzbol, but it is generally a good idea to have one.
Inheritance rules are very different, particularly in the absence of a will executed according to halachic specifications. Generally sons inherit to the exclusion of their sisters, among other differences. There are provisions that may be included in a will allowing it to be enforceable under Jewish law. Also, if the parties to a litigation stipulate that the provisions of a will should be honored, the Beth Din will respect the provisions of the will.