In this article, Paul Moreno explores the role of natural law in Supreme Court decisions. “Natural-law jurisprudence” encompasses an idea of natural law that is far broader than any of the natural law traditions included on the website, and involves a judge’s resort to any “higher law,” anterior and superior to the written constitution. He traces this broad idea of natural law from the Declaration of Independence’s claims about “self-evident truths” of human equality and the necessity of consent, to the Court’s recent 1992 assertion that at “the heart of liberty is the right to define one’s own concept of existence.” Many Supreme Court justices have based their decisions forthrightly on natural-law arguments, appealing to what they argue are well-known principles of reason and justice. Others have found a textual basis for natural-law arguments in the Constitution’s contract clause, the 5th Amendment’s “due process of law” clause, and the 14th Amendment’s reaffirmation that no state can deny “the equal protection of the law” to any person. Opponents of natural law jurisprudence argue that it imports into constitutional interpretation political and economic theories external to the Constitution’s text. Critics such as Justice Black also argue that decisions which appeal to universal principles are only based on subjective considerations of natural justice.