The Sefer Mayim Rabim (Amsterdam, 1737) is a four-volume collection of halakhic responsa by rabbi Raphael Meldola (1685-1748). Originally from Livorno, Meldola served as rabbi in Bayonne between 1721 and 1741. Despite his sometimes difficult relationship with the parnasim (lay leaders) of the Livornese Jewish community, Meldola dedicated the third and fourth parts of his Mayim Rabim, dealing with halakhic questions of Even hazer (family law) and Hoshen mishpat (civil and criminal law), to them. This Spanish "dedicatoria," which does not appear in all editions of the book, sheds light on the complexities of early modern Jewish communal authority.

In a move common to early modern dedications, Meldola confers quasi-authorship to the parnasim. Meldola states that he ought to dedicate the book to the parnasim since he received the title of "dayan" from them in March 1710. He adds that the subject of the book matches their duties, as the Livornese lay leaders can adjudicate civil causes, "a unique privilege that they enjoy, in contrast to other communities, through the special grace of His Royal Highness [the Grand Duke of Tuscany]." Most intriguingly, Meldola remarks that "a great part of the legal questions proposed in these volumes were already discussed and adjudicated in your illustrious maamad." For this reason, the book's cases will gain even greater acceptance "being res judicata." It is known, however, that the Livornese parnasim generally employed state and municipal law to adjudicate questions not strictly pertaining to the Jewish ritual sphere, such as commercial disputes in civil law cases, while the cases discussed in the volumes are approached through the lens of halakhah. Meldola's words thus offer tantalizing glimpses into possible tensions and overlaps between lay and rabbinic jurisdictions and into the competing authority of state and municipal law, on the one hand, and halakhah, on the other hand, in early modern Jewish communities.