Definition
The rule of law is a foundational constitutional and political principle holding that law — not the arbitrary will of individuals or officials — governs society. It operates on two levels that legal research must keep distinct:
1. As a governing ideal: The principle that all persons, institutions, and governmental actors are subject to and accountable under law that is publicly known, equally applied, independently adjudicated, and consistent with human dignity. In this sense, the rule of law is a constitutional norm invoked to evaluate the legitimacy of legal systems and the conduct of governments.
2. As a technical legal term: A general principle of law, recognized by authoritative sources, used to guide the resolution of new or doubtful cases. In this narrower and older sense — the sense preserved in Bouvier and Black's — "rule of law" refers not to a governing ideal but to an established legal norm functioning as a decisional standard. It is called a "rule" because it rules: it provides a norm by which particular cases are judged.
These two meanings coexist in the literature and are frequently conflated. Research context determines which is operative.
---
Common Language
Modern common usage (Wiktionary): The doctrine that no individual is above the law and that everyone must answer to it; the maxim that governmental decisions are made by applying known legal principles.
Historical common usage (Webster's 1913): Webster's 1913 does not carry a distinct entry for "rule of law" as a compound term; the phrase would have been understood compositionally from its parts.
The gap between common and legal meaning here runs in a specific direction. Popular usage has converged on the political-philosophical sense — the rule of law as a check on tyranny and official arbitrariness. Historical legal usage, reflected in Bouvier and Black's, was considerably more technical and narrower: a rule of law was an established general legal principle used to decide cases, akin to a maxim. A researcher encountering "rule of law" in a nineteenth-century legal treatise should not assume the author is invoking the broad constitutional ideal; they may simply be pointing to an authoritative general principle of decision.
---
Common Confusion
Rule of law (governing ideal) vs. rule of law (technical term): As noted above, the same phrase carries two distinct and largely non-overlapping meanings depending on era and context. Nineteenth-century legal dictionaries use the term in the technical sense. Twentieth- and twenty-first-century constitutional law scholarship, comparative law, and international law instruments use it in the political-philosophical sense. Neither usage is wrong, but reading one into the other produces serious interpretive error.
Rule of law vs. rule of man: The rule of law is classically defined against the "rule of men" — governance by personal will or discretion rather than by established legal norms. This contrast, prominent in Aristotelian political philosophy and carried into constitutional theory, shapes how the term is deployed in historical sources. Researchers working in political and constitutional history will encounter this framing frequently.
Rule of law vs. supremacy of law: These are near-synonyms in constitutional usage but not identical. Supremacy of law emphasizes the hierarchical priority of law over other forms of authority. Rule of law additionally encompasses procedural dimensions — accessibility, certainty, equal application, independence of adjudication — that supremacy alone does not capture.
---
Core Elements
In its governing-ideal sense, the rule of law is understood to encompass several overlapping dimensions, though formulations vary across sources:
Generality and publicity: Laws must be general in application and publicly known before they are enforced. Secret or retroactive law is inconsistent with rule-of-law norms.
Equality before the law: No person or institution — including government officials — is exempt from legal obligation. This is the dimension most prominently preserved in popular usage.
Legal certainty: The law must be sufficiently clear and stable that individuals can plan their conduct in reasonable reliance on it.
Independent adjudication: Disputes about the application of law must be resolved by tribunals that are independent of the parties, including the government as a party.
Procedural fairness: Legal processes must meet minimum standards of notice and opportunity to be heard.
These elements are analytically useful but not formally enumerated in any single binding source. Different legal traditions weight them differently.
---
Why It Matters in Research
The term demands a threshold disambiguation every time it appears in a source. Ask first: Is this source using "rule of law" in the technical sense (an established legal principle for deciding cases) or the constitutional-ideal sense (a norm of legitimate governance)? The answer almost always tracks the era of the source and its disciplinary context.
In pre-twentieth-century legal dictionaries and treatises, "rule of law" typically signals the technical meaning. Bouvier's entry cross-references Blackstone and the common law maxim literature; Black's cites Toullier, a French civil law treatise. Researchers working in these sources should treat "rule of law" as roughly equivalent to "established legal principle" or "general maxim of law" — and follow the cross-reference to MAXIM or RULE for fuller treatment.
In modern constitutional law, international law, and comparative law scholarship, "rule of law" almost always signals the political-ideal sense. This usage became dominant in Anglophone legal scholarship largely through the influence of A. V. Dicey's constitutional analysis in the late nineteenth century, which gave the phrase its modern shape and global currency. Researchers who encounter a sudden shift in register around Dicey-era materials are tracking a genuine historical inflection point.
The term also appears in judicial opinions across multiple contexts. Courts sometimes invoke it rhetorically (as a constitutional value), sometimes technically (as shorthand for a specific established principle), and occasionally in ways that conflate both. Tracing which usage a court intends requires attention to the surrounding argument, not just the phrase itself.
For corpus researchers: the Law Mind sources are not strong resources for the political-ideal sense, which is developed primarily in constitutional law scholarship, political theory, and international legal instruments outside the historical dictionary tradition. The dictionary sources here are most useful for the technical sense. Researchers pursuing the constitutional-ideal sense should treat the dictionary entries as a starting point only and expect to work outward into constitutional and comparative law materials.
---
Historical Dictionary Support
All three source dictionaries treat "rule of law" in its technical, narrower sense — as a general legal principle recognized by authoritative sources and applied to govern new cases. This is consistent with their era and function as legal dictionaries oriented toward practice and doctrine.
Black's and Bouvier's are substantively in agreement: both define the term as a general principle of law, authoritative by recognition, called a "rule" because it guides decision in doubtful cases. Bouvier adds the clarifying function more explicitly — "it embraces particular cases within general principles" — which usefully distinguishes a rule of law from a mere maxim by emphasizing its organizing, subsumptive role.
Rapalje & Lawrence defers entirely to their entry on RULE, offering no independent treatment. This is a gap. Researchers using Rapalje as a primary source will need to supplement with Bouvier or Black's for any substantive content on this term.
Black's citation of Toullier is notable: Toullier was a French civil law scholar whose work on the relationship between general legal principles and their application to new cases was well regarded in the Anglo-American tradition. The citation signals that "rule of law" in this technical sense was understood as a cross-system concept, not peculiar to common law.
What none of the historical dictionaries address — and what the modern researcher most needs — is the political-ideal sense. The Diceyan formulation of rule of law, the international rule-of-law literature, and the constitutional dimensions of the concept are entirely absent from these sources. They are not a deficiency of the dictionaries; they are a consequence of the historical moment of their composition. Researchers should read the silence as a dating signal, not as evidence that the political meaning is secondary.
---
Jurisdictional Note
The rule of law in its governing-ideal sense is a trans-jurisdictional principle, but its specific content varies. Common law systems, civil law systems, and international legal instruments each operationalize it differently. Within the United States, the principle is expressed through constitutional supremacy, separation of powers, and due process requirements; no single clause carries the label "rule of law," but the concept underlies much of constitutional doctrine. Researchers moving between domestic and comparative or international law materials should not assume that the same phrase signals the same institutional commitments.
---