On July 4, 1776 the Continental Congress of the United Colonies declared to the world that all men are created equal, and are endowed by their Creator with certain inalienable rights, among them life, liberty, and the pursuit of happiness. The language of the Declaration of Independence was clearly inspired by the Virginia Declaration of Rights adopted nearly a month before on June 12.
Both documents obviously espoused an Aristotelian understanding of the natural law as refined by the Medieval scholastic philosophers, notably Thomas Aquinas. Robert Bellarmine, a 17th century Italian Catholic Cardinal, translated this into the idiom of modern political science. This was a result of his struggle against proponents of the divine right of kings, and transmitted to the revolutionaries largely through the work of John Locke and Algernon Sidney.
The basis for the new government was thus clearly derived from "Catholic" political theory: the natural law based on God's Nature and reflected in human nature, not someone's opinion about something that might or might not be an expression of God's Will. There was, however, a serious problem thrown into the mix: chattel slavery.
Defenders of slavery were quick to point out that slavery is not contrary to the natural law. That is absolutely correct. The problem was that, to be in conformity with the natural law, the enslaved individual has to be personally guilty of some crime for which slavery is imposed as punishment and a means of rehabilitation. To impose or maintain slavery based on the alleged inability of a single individual, much less an entire group, to function as free people, absent actual crimes of which they are personally and individually guilty, is directly contrary to natural law. You cannot punish people for something they might do. You can only punish someone for what he or she has actually done — and for which you have demonstrable proof.
Thus you had a conflict built into the constitution of the new country from the very beginning. Everything in the new Constitution except slavery was clearly established on a solid foundation of the natural law as found in Aristotelian philosophy corrected by Aquinas. In order to protect slavery, however, distortions and even contradictions became the order of the day. This caused problems that have lasted down to the present day, reaching what many regard as their epitome in Roe v. Wade.
According to William Crosskey, the perceived need to preserve slavery was behind the development of the theory of "state's rights" and the expansion of "judicial review" far beyond the intent of the framers of the Constitution. This promoted an encroachment by the Supreme Court on the powers of Congress before the Civil War in an effort to placate the politically powerful South, and after the war in opposition to the growth of the power of the Executive and the diminution of the power of Congress.