This paper offers a comparative reflection on Western constitutionalism and the Constitution of the Islamic Republic of Iran (1979, amended in 1989), using the tension between positive law and natural law as its guiding framework. It argues that, within the contemporary Western paradigm, freedom increasingly takes the form of subjective self-determination detached from truth, objective good, and any intelligible natural order, thereby reinforcing the sovereignty of positive law and fostering a procedural conception of dignity. As a result, “humanity” risks becoming a malleable legal construct, vulnerable to cultural relativism, shifting ideological trends, and judicial balancing techniques, with constitutional principles losing stable substantive grounding. By contrast, the Iranian constitutional model is reconstructed as a theonomic architecture in which sharīʿa functions as both foundational principle and ultimate limit of validity for the legal order; freedom is understood as adherence to divine order rather than arbitrary autonomy, institutionally safeguarded through mechanisms such as velāyat-e faqīh and the Guardian Council’s review of legislation. The critical comparison highlights the internal coherence of a transcendentally grounded legal order and exposes the Western drift toward juridical and anthropological nihilism. The paper concludes by advocating a renewal of Western legal thought through an ontological re-foundation of law, recovering natural law as a superior critical criterion capable of orienting and judging positive norms.