How does natural law differ from positive law?

In the philosophy of law, the distinction between natural law and positive law centers on the source of legal authority and the criteria for a law's validity.

Natural law is defined as a system of right or justice held to be common to all humans and derived from nature, reason, or objective moral truths rather than from human-made rules. Proponents of natural law, such as St. Thomas Aquinas, argue that valid positive law must be derived from these moral principles. From this perspective, if a human-enacted statute is fundamentally unjust and fails to align with these moral truths, it may be considered a failure of law, lacking binding moral authority.12

Positive law, by contrast, refers to laws established or recognized by governmental authority. It is "formally laid down or imposed" by human institutions, such as a legislature, rather than being inherent in nature. Legal positivists, such as Hans Kelsen, maintain that the normative force of law derives from the legal system itself—such as a constitution or basic norm—rather than from its moral status. Consequently, positive law can exist and be enforced even if it is not morally justified.345