For law to possess authority and function as the ultimate source of obligation, it must remain independent of other normative realities. Conditioning its validity upon the normative reality of Sharia—or any other normative realities—leads to a “crisis of disproportionate authority” and inevitably results either in the weakening of both legal and religious authority or, in practice, in reducing law to a mere instrument for enforcing a particular interpretation of Sharia.
However, the impossibility of a co-existing and proportionate authority of law and Sharia does not imply the exclusion of Sharia from the legislative process. Law, as a product of social facts, has a non-contingent existence; in this respect, Sharia may enter the process of lawmaking, provided that it is considered not as a normative reality and a criterion of legal validity, but as a social reality—that is, insofar as it is reflected in the beliefs and practices of the members of society.
By distinguishing between Sharia as a normative reality and Sharia as a social reality, this article examines the theory of Mohammad Hossein Na’ini as a prominent example of the theoretical efforts of religious constitutionalists, and demonstrates why attempts to establish a form of proportionality between the authority of law and Sharia—both in the Constitutional era and thereafter—are bound to fail. It is finally argued that only through this distinction, and by recognizing Sharia as a social reality, can the authority of law be both realized and preserved, while also making possible the just governance of a plural society with due respect for individual rights and freedoms.