Natural law theory asserts the purpose of law is to serve a higher morality, foster necessary qualities of good people, and promote the common good. In “Letter from Birmingham Jail,” Martin Luther King Jr. argues that an unjust law, a code that is inconsistent with the moral law, is no law at all. From this reasoning, it follows that morality is not only a sufficient, but also a necessary criterion by which to judge human law. Natural law represents an intrinsic quality of all law that is just.
However, in thinking about our current legal system, it becomes evident that this is not the case. There are many laws that do not serve an obvious moral purpose. Take clothing for instance. Clothing-related laws fall under various offenses set by different states such as “indecent exposure”, “public lewdness”, “public indecency”, “disorderly conduct”, etc. Regardless of what it’s called, the point is that it’s illegal to walk around naked in the United States. Does clothing advance the common good? Are we infringing upon individual freedoms by forcing citizens to hide their bodies? Don’t we criticize other cultures for requiring women to cover specific areas? There are many plausible arguments against mandating clothes, but the fact remains that most people associate clothing with morality. Why is this the standard? To determine this, it’s necessary to assess the very nature of natural law—where it comes from, what it means, and, finally, if it is actually a sufficient criterion by which to judge positive law.
Thomas Aquinas defines natural law as “…nothing else than the rational creature’s participation in the eternal law”. He claims that, “the natural law is promulgated by the very fact that God instilled it into man’s mind so as to be known by him naturally.” As a priest of the Roman Catholic Church in the 13th century, Aquinas is basing his statements on religious doctrine that assumes that all people, in all places, at all times hold the same truths to be “natural”. Today, it appears that most conceptions of natural law are derived by way of tradition, history, and the privileged hegemonic ideology of the Judeo-Christian religion. From this standpoint, there is really nothing “natural” about it. We simply put our faith in the power of authority so that we may understand what is really a socially constructed foundation for morality as an intrinsically natural law of life. According to Aquinas, the first precept of natural law is that “good is to be done and pursued, and evil is to be avoided”. But since natural law may not actually be natural, “good” is not an absolute truth. It may mean different things to different people.
One example that highlights this ambiguity of natural law is birth control. If we consider sex from a natural law perspective, one based on the will of God, a predominant view is that sex is exclusively for the purpose of reproduction. For a good portion of American history, this was the opinion of the overwhelming majority. Birth control was not legal in all states until the middle of the 20th century. The government denied women the right to determine when they had children, how many children they had, and, at times, with whom. If a woman was engaging in sex, it was in order to reproduce. Not only is contraception “unnatural” from a biological point of view, but it may also be understood as inconsistent with the Eternal law of how men and women should act. Birth control may very well be constructed as an evil that directly contradicts the law of God, but it also serves to enhance life for women, men, and the community as a whole. It grants women autonomy over their reproductive rights, allows couples to decide if and when they have children, prevents unwanted pregnancy, and offers children a better quality of life. The legality of birth control may oppose natural law, but it nevertheless promotes the common good as we understand it today.
If natural law is not always synonymous with the common good, then how can we trust it as a sufficient criterion by which to judge human law? That’s not to say that morality is not an important aspect of our legal system, but rather to suggest a reevaluation of our understanding of natural law and how it’s been shaped by a history of religious tradition. Maybe our conception of natural law will one day be seen through a more objective, truly “natural” lens, that will allow for a better standard for judging our human laws. But at this point in time, it doesn’t seem to be the case.