The Collaborative International Dictionary of English v.0.48:

Lawgiver \Law"giv`er\, n.
   One who makes or enacts a law or system of laws; a
   legislator.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lawgiver
    n 1: a maker of laws; someone who gives a code of laws [syn:
         lawgiver, lawmaker]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "lawgiver":
   MP, Member of Congress, Member of Parliament, alderman,
   assemblyman, chosen freeholder, city father, congressman,
   congresswoman, councilman, floor leader, lawmaker, legislator,
   majority leader, minority leader, party whip, representative,
   senator, solon, state senator, whip