This paper explores the relationship between Law, Morality, and Politics in the work of Carlos S. Nino, focusing on his conception of legal duties and democratic legitimacy. Nino seeks to overcome the historical dichotomy between Natural Law and Legal Positivism by proposing a theory that links the normativity of Law to ethical principles, arguing that legal norms can only be legitimate if they stem from democratic deliberative processes. The paper analyzes Nino's thesis of the plurality of legal concepts and the special case thesis, where legal discourse is understood as a specification of ordinary moral reasoning. In this framework, legal duties are not autonomous but are grounded in ethical duties, which provide them with legitimacy. Additionally, the connection between Law and Politics is examined through the lens of deliberative practice, which Nino regards as the essential mechanism for ensuring a legitimate legal system. The implications of constitutionalism and human rights in this context are discussed, emphasizing their role as normative principles that strengthen justice and equity. The obligation to obey the law is justified only when it emerges from a democratic and deliberative process that morally legitimizes it, ensuring its alignment with the core values of a pluralistic society.