The other work is on Jewish Law , halakha , known as the Shulchan Aruch HaRav , the "Code of Law of the Rav" . His work is the halkhic foundation of all Hasidism, and is used as referenced by scholars and laymen. Citations are routinely found in such varied sources as the Mishnah Berurah and Ben Ish Chai.
Descendents of Rabbi Zalman adopted the names Schneersohn or Schneerson to accommodate Napoleonic edicts that required all subjects to take permanent surnames. (Prior to Napoleon's conquests and the winds of Enlightenment he brought in his wake, Jews only had their traditional names such as Shneur ben (son of) Boruch.) The last two Rebbes of Chabad Lubavitch, Rabbi Joseph Isaac Schneersohn (1880-1950) and Rabbi Menachem Mendel Schneerson (1902-1994), living in modern times, adhered strictly to their family surnames.
Dovber of Mezeritch