Is a Moral Theory of Law Misguided? Natural Law Explained


Morality has the distinct honor of being a concept found and refound in discussions on legal theory. Let’s break — morality and legal theory are, to be sure, two dense, varied, and widely-studied topics. 500, or even 1000 words, covering the two dominant philosophies governing how law is made just barely puts a dent in the mountains of existing literature on the topic. This post, and its successor, are not advancements of competing theory, but rather serve as primers, explaining the ways in which people have thought, and hope to think, about creating and enforcing legal codes. Now, let’s dive right in:

A branch of philosophy dating back to Thomas Aquinas, Natural Law broadly advocates the notion that, “an unjust law is not a law.” With an definition of legality coming from the ability of lawmakers to understand nature and the world itself, this theory emphasizes morality. As such, the natural world, astronomy, physics, contemporary ethical beliefs, and religion (in the form of Divine Law) guide ideas about just and unjust expressions of the law. Theorists aligned with this mode of thinking may argue roughly this set of points: (a) that law should be made with consideration of nature and inherent values of right and wrong, and (b) that laws out of compliance with moral considerations are invalid and should not be respected.

Aquinas—the theorist whose work is most associated and celebrated within Natural Law theory—believed that law, a system of rules of divine function, would not exist in the event that a statute could be considered a moral wrong. His famous postulation that “an unjust law is not a law” endures to this day as a rallying cry of morally-minded speculators.Though Natural Law as an identifier constitutes an older group of theorists, the idea itself remains viable. Evidenced, for example, in works like MLK’s “Letter from Birmingham Jail,” is an adherence to the same principle that laws which violate morality are, or should be, considered invalid. His letter, one of the most famous texts to come from the Civil Rights Movement, highlighted the injustice of Jim Crow in the Southern United States, notably claiming the truth that injustice anywhere is injustice everywhere. A notion is steeped in moral consideration, the idea that unjust laws are difference made legal, while just laws are such because they advance the law of sameness is a modern iteration of an early-modern concept.

Natural Law theory asserts that there are moral laws written into the fabric of human existence. As a race, we do not create what is right or wrong, but rather discover objective truths related to equality and legal rights over time. Moral law is simply an avenue by which a society can gage its progress, shortcomings, and failures. In King’s influential example, the injustice of the American system is challenged in his discussion on segregationist laws. Cementing the distance from American idealism towards the pursuit of justice, liberty, and freedom for all, King’s writing on morally-minded law provoked meditation — and lively discussion — on the nature of American law and the ways in which law should and can be made. This discussion endures to the present, and brings with it competing theories regarding equality, legality, and moral salience. 

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