If the great legacy of King Benjamin was his sermon from the tower, then the legacy of his son, Mosiah, was the Nephite legal system. He had abolished his own monarchy, established a system of judges, founded society on democratic principles, and 'established laws' which 'were acknowledged by the people' (Alma 1:1). Hugh Nibley referred to the laws of Mosiah as the Nephite "constitution," and the speech of king Benjamin as their "bill of rights" (See Teachings of the Book of Mormon, Lecture 75, p. 222).
Those of us who are privileged to live in a country in which there is legal stability sometimes forget how important just laws are. When the Nephites begin to alter these laws, they begin to destabilize the very foundation of their society.
"Although the law of Mosiah allowed the people to select judges, it does not appear that these judges had the power to create law itself. The law that they applied was 'given them' by Mosiah (Mosiah 29:39), and the laws under which they acted were remembered several generations later as the 'laws of Mosiah' (Helaman 4:22).
"Like other ancient lawgivers, who often drew on divine sources in legitimizing their laws, Mosiah gave the laws 'which the Lord commanded him to give unto the people' (Helaman 4:22). For example, Moses issued the laws that Jehovah revealed to him, and Hammurabi claimed on his stele that the god Marduk had 'called' him 'to make justice to appear in the land' and commanded him 'to set forth truth and justice' by establishing his laws.
"The law of Mosiah primarily made procedural changes and probably did not make radical changes in the substantive rules of the law of Moses. Mosiah instructed the new Nephite judges to judge 'according to the laws . . . given you by our fathers' (Mosiah 29:25; italics added), and twenty-two years later the Nephites were still 'strict in observing the ordinances of God, according to the law of Moses' (Alma 30:3)." (John W. Welch, Reexploring The Book of Mormon, pp. 158-9)