Definition
The law of nature is a body of moral and legal principle held to derive from the natural order of human relations, reason, or divine will, and understood to exist independently of — and prior to — any enacted or positive law. In legal usage, it operates at two distinct levels:
1. As a philosophical foundation: A pre-political standard against which positive law is measured. Writers in this tradition hold that rules governing human conduct are discoverable through reason and, in theistic formulations, reflect the will of the Creator. Obligations so derived bind individuals and governments alike, regardless of whether any legislature has codified them.
2. As a practical legal concept: A residual source of obligation invoked when no enacted rule governs a dispute — particularly in early common law, admiralty, international law, and equity — where courts appealed to natural law principles to fill gaps or to void rules deemed fundamentally unjust.
The term is used interchangeably with natural law and, in Latin sources, with jus naturae or jus naturale.
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Common Language
Modern common usage (Wiktionary): A scientific generalization about nature based on empirical observation — as in the law of gravity — or, secondarily, a generally shared moral principle.
Historical common usage (Webster's 1913, as reflected in the historical legal dictionaries): A rule of conduct arising out of the natural relations of human beings, established by the Creator, and existing prior to any positive precept.
Editorial note: The gap here is substantial and potentially misleading. A modern reader encountering "law of nature" in a scientific or philosophical text understands a descriptive empirical regularity — something that cannot be violated. In legal sources, the phrase carries an entirely different, normative meaning: a prescriptive standard of conduct that ought to govern behavior precisely because it can be violated. When historical legal texts invoke the law of nature, they are not making a claim about physics; they are asserting the existence of binding moral obligations prior to statute. Researchers reading nineteenth-century and earlier legal materials must hold this distinction firmly in mind.
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Common Confusion
LAW OF NATURE vs. LAW OF NATIONS: These two concepts are closely associated in classical jurisprudence and are sometimes treated as nearly synonymous, but they are not. The law of nature is the universal moral baseline applicable to all rational beings by virtue of their nature. The law of nations (jus gentium) is the body of rules that, derived partly from natural law and partly from custom and consent, governs the relations among states and peoples. Natural law is the source or standard; the law of nations is the derived and applied superstructure. Historical dictionaries frequently present them in sequence, which can blur the distinction for researchers reading quickly.
LAW OF NATURE vs. NATURAL RIGHTS: The law of nature describes the governing standard or rule; natural rights are the entitlements or claims that flow from that standard. A right to self-preservation, for example, might be said to be a natural right because the law of nature prescribes conditions for human flourishing. The terms are conceptually linked but not interchangeable.
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Why It Matters in Research
The law of nature is a foundational concept that does not behave like a modern statutory or common-law rule, and researchers must approach it with corresponding care.
First, the term functions differently across legal subfields. In contracts and equity, appeals to natural law historically provided grounds for refusing to enforce unconscionable agreements or for implying obligations that no statute created. In constitutional theory, natural law arguments underpinned early debates about unenumerated rights and the limits of legislative power. In international law, the law of nature was, until the positivist turn of the nineteenth century, a primary source of authority. The same phrase, in the same period, could carry different analytical weight depending on which court or writer was invoking it.
Second, the concept undergoes dramatic transformation across time. Pre-nineteenth century legal sources treat natural law as a live source of binding obligation — courts and treatise writers appeal to it directly. By the late nineteenth century, the positivist reaction (associated with figures such as Austin and Bentham) had largely displaced natural law from technical legal argument, relegating it to moral philosophy. A researcher reading Blackstone alongside a late-Victorian contract treatise will find the phrase doing entirely different work in each.
Third, the theistic framing is pervasive in historical sources. Black's, Bouvier's, and Burrill's all root the law of nature in divine will and right reason. Researchers should not assume this framing is merely rhetorical — these writers believed it carried genuine legal force. But they should also recognize that the same underlying claims were later reformulated in secular terms (rational consensus, human dignity, social contract), and that these reformulations appear in twentieth-century constitutional and international law scholarship without always acknowledging the theological heritage.
Fourth, citation patterns in historical legal texts frequently invoke the law of nature as if it were self-evident authority. Burrill cites Taylor's Civil Law; Bouvier reasons from it to specific duties. Neither offers what a modern researcher would recognize as a testable source. Treat these invocations as statements of jurisprudential position, not as citations to governing authority.
Finally, the connection between natural law and foundational legal instruments — declarations of rights, constitutional preambles, early federal court opinions — makes this concept a necessary reference point for researchers working in constitutional history, human rights law, and the intellectual history of common law courts.
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Historical Dictionary Support
Black's, Bouvier's, and Burrill's present a notably consistent picture for a concept this contested in philosophy. All three root the law of nature in the will of God, discovered through right reason and supplemented by divine revelation. Burrill adds the Latin equivalents (jus naturae, jus naturale) and cross-references Taylor's Civil Law, grounding the definition in the civil law tradition. Bouvier is the most expansive, extending the concept to encompass duties owed to God, to oneself, and to neighbors — a tripartite structure with roots in scholastic and Thomistic moral theology.
The dictionaries agree that natural law is prior to and independent of positive law, and that its principles bind states and individuals equally. This is the classical natural law position, and all three sources reflect it without reservation or qualification.
What the historical dictionaries do not address is the sustained positivist challenge to natural law that was already well underway by the time these editions were published. Neither Black's nor Bouvier's acknowledges Austin's command theory or the growing academic consensus that "law" properly so called requires a sovereign source. For a research library whose corpus includes both pre- and post-positivist materials, this silence in the historical dictionaries is itself informative: these reference works were written in a tradition that treated natural law as a legitimate legal category, not merely a moral aspiration. Researchers should not assume that legal writers who cite natural law in the nineteenth century were being loosely philosophical — within the tradition these dictionaries represent, the invocation had genuine jurisprudential content.
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Jurisdictional Note
Natural law has never been a statutory category in any common law jurisdiction, but its influence on American constitutional interpretation has been debated continuously. Early Supreme Court opinions invoked it; later positivist-influenced courts resisted it. In international law, natural law foundations persist in human rights instruments and customary international law doctrine in ways that do not map cleanly onto domestic jurisdictional lines.
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