In this article, Michael Pakaluk outlines how Aristotle’s thought has contributed to the natural law tradition, and in particular its influence on the American founders. Aristotle’s arguments about republican forms of government were especially compelling for the Founders and he was credited as the source for many of the foundational doctrines of the American Republic. The Founders also relied heavily on Aristotle’s views about the rule of law, which was understood to be connected to natural justice and to involve the consistency and harmony of human law with the “law of nature.” Since the claims of justice in human affairs are conventionally justified by an appeal to a standard of equality, Aristotle understood “natural justice” to be a claim about what is just that appeals instead to “the nature of things.” Because natural justice must then be based on the laws of nature, Aristotle understood justice and “lawfulness” as interchangeable. In other words, just as natural justice takes priority over conventional justice, natural law is by extension of a higher authority than conventional law. This is born out by Aristotle’s belief that natural law may be invoked as grounds for disobeying a contravening human law, as well as his recognition of “moral absolutes”: actions which must never be done if one is to live in accordance with the laws of nature.