Natural law is a philosophy asserting that certain rights are inherent by virtue of human nature, endowed by nature—traditionally by God or a transcendent source—and that these can be understood universally through human reason. As determined by nature, the law of nature is implied to be universal, existing independently of the positive law of a given state, political order, legislature or society at large.
Historically, natural law refers to the use of reason to analyze human nature to deduce binding rules of moral behavior from nature's or God's creation of reality and mankind. The concept of natural law was first documented in ancient Greek philosophy, including Aristotle, and was referred to in Roman philosophy by Cicero. It was then alluded to in the Bible, from which it was subsequently developed in the Middle Ages by Catholic philosophers such as Albert the Great, and Thomas Aquinas. In the Renaissance, notably the School of Salamanca further contributed. During the Age of Enlightenment, modern era natural law theories were further developed, combining inspiration from Roman law, and alongside philosophies like social contract theory.
It featured greatly in the works of Alberico Gentili, Francisco Suárez, Richard Hooker, Thomas Hobbes, Hugo Grotius, Samuel von Pufendorf, Matthew Hale, John Locke, Francis Hutcheson, Jean Jacques Burlamaqui, Emmerich de Vattel, Cesare Beccaria and Francesco Mario Pagano. It was used to challenge the divine right of kings, and became an alternative justification for the establishment of a social contract, positive law, and government—and thus legal rights—in the form of classical republicanism. Conversely, the concept of natural rights is used by others to challenge the legitimacy of all such establishments. Natural law description sourced from Wikipedia.