Invocations of natural law in contemporary legal circles are almost guaranteed to generate more heat than light. Proponents frame natural law as essential to the defense of civilization and its critics as perversely denying universally accessible truths; critics regard natural-law discourse as a Trojan horse for the imposition of a minority’s conservative religious convictions on an increasingly pluralistic nation. The idea that common law – the stuff of quotidian courtrooms in America – might be in fundamental harmony with natural law, or even structured and justified by it, is accordingly fantastical or nightmarish. This was not always so. Despite today’s prevailing wisdom that common law and natural law are separate and distinct ideas, in reality, a centuries-long stream of American legal thought presupposed – sometimes tacitly, sometimes explicitly – that natural law and common law are intertwined. Natural law, in short, undergirded the development of American jurisprudence. Contemporary debates on law, morality, and religion lack this historical memory and suffer accordingly.