A Thomistic Perspective on Natural Law Reasoning in the Supreme Courts

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Ohio Northern University Law Review


Natural law plays a prominent role among the various sources of the common law used by supreme court justices. Decisions by the Supreme Court of the United States and the supreme courts of the several states mention it directly by name in over 1400 cases. Yet there is relatively little explanation of the term in most of the decisions. Justices write as if the term is widely understood, but the controversy that has ensued over the use of natural law as a source of the common law suggests that it means different things to different justices. Some justices condemn the use of natural law as a mode of arbitrary decision-making. Other justices extol its use as a source of judgment higher than other sources. This article will examine the meaning of natural law as these justices use it. The preeminent source on natural law is the Summa Theologiae written by St. Thomas Aquinas in the thirteenth century. It provides a simple, but powerful, explanation of natural law as the light of human reason by which a person "discern[s] what is good and what is evil." The human reason apprehends good or evil from "things to which [a person] has a natural inclination" or repulsion, and the human will inclines towards the former and away from the latter as an end. Aquinas defines this direction that human reason gives to a person as the precepts of the natural law by which a person knows that something is to be done or avoided.' However, because human judgment is uncertain, God revealed the Divine Law of the Old and New Testament so that a person could know without doubt what is to be done and what is to be avoided. Thus the Ten Commandments contain several moral precepts which reflect the precepts of the natural law. In fact, all the precepts of the natural law are either so evident that they need no promulgation, such as the precept to love God and neighbor, or they appear in the Decalogue, such as the prohibitions of murder, adultery and theft, or they are reducible to the precepts of the Decalogue as corollaries, such as the prohibitions of hatred, bestiality, and fraud. A review of the opinions of federal and state supreme court justices who refer to natural law reveals that, despite the fear by some that it will be used as an excuse for arbitrariness, they generally affirm natural law as a source of human law. Furthermore, the precepts that these justices espouse as precepts of the natural law generally fall within the precepts of the first eight of the Ten Commandments: (I) Thou Shalt Worship the Lord Thy God; (II) Thou Shalt Not Take the Name of the Lord Thy God in Vain; (III) Keep Holy the Lord's Day; (IV) Honor Thy Father and Thy Mother; (V) Thou Shalt Not Kill; (VI) Thou Shalt Not Commit Adultery; (VII) Thou Shalt Not Steal; and (VIII) Thou Shalt Not Bear False Witness. The two Commandments whose precepts the courts do not mention-(IX) Thou Shalt Not Covet Thy Neighbor's Wife and (X) Thou Shalt Not Covet Thy Neighbor's Goods address the moral goodness of one's interior thoughts, an area that unsurprisingly remains outside the domain of human law. This article organizes the opinions on natural law according to the respective Commandments they follow in order to. illustrate the rich tradition of natural law which our country's justices have developed throughout its history.

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