The laws of sheviit are tagged as coming from har Sinai in order to convey the message that these laws are meant not only to be followed but more important they are meant to function as definimg the cultural shape of the nation.
Sheviit must take on the color of the covenant between God and the people of Israel.
As the Sinaitic covenant defines the character of the nation, so these laws must serve as the germs for implementing the institutional sub-structure of such a nation. Sheviit is about more than a set of laws governing the use of land in Israel, it is about a vision of what a covenantally autonomous people can accomplish.
It is a stab at utopia; it is the biblical regime’s shot at making a paradise on Earth.