There are those who say that American law is based only on what legislators determine it to be and what judges interpret it to mean. They claim that enacted or positive law is the only real basis for law in the United States.
However, this is not the American tradition. The foundation of the American legal philosophy is based on natural law, which is valid for all times and all peoples. Since colonial times, any law, whether enacted or customary, had to conform to natural law if it was to be considered valid.
This theory goes back even farther than colonial times since it is based on medieval law and even to Aristotle. Just as American law has to stand the test of being in accordance with the Constitution, so also early American law was judged by its conformity to this higher natural law tradition.
Indeed, the very Constitution itself has natural law references. Take for
example, the phrase “due process of law” found in the American Constitution. Harold J. Berman writes that “‘Due process of law’ is, in fact, a fourteenth century English phrase meaning natural law. Thus, natural-law theory is written into the positive law of the United States” (Harold J. Berman, Law and Revolution: The Formation of the Western Legal Tradition, Harvard University Press, Cambridge, Mass., 1983, p. 12).