Definition
In law, principles are the foundational truths, doctrines, or comprehensive rules from which more specific legal rules derive their authority and coherence. The term operates at several levels of abstraction:
1. Axiomatic or self-evident propositions: Truths so fundamental that they require no formal proof and cannot be contradicted except by propositions even more basic — the bedrock assumptions on which legal reasoning rests. Examples include the maxim that no one may transfer greater rights than they possess.
2. Doctrinal foundations: Comprehensive legal rules or doctrines that generate and organize clusters of subordinate rules. General principles of contract, equity, or agency belong here — not case-specific holdings, but the organizing logic beneath them.
3. Settled rules of action or procedure: Standards of conduct or decision that, through sustained application, have acquired the weight of governing authority without necessarily rising to the level of enacted law.
Principles are distinct from rules in degree rather than kind: a principle states a general truth or direction; a rule typically operationalizes that truth in a specific, enforceable command. Principles are also distinct from policies, which are forward-looking justifications for outcomes rather than inherited legal truths.
Common Language
Modern common usage (Wiktionary): Plural of principle — broadly, fundamental beliefs, values, or doctrines guiding conduct or reasoning.
Historical common usage (Webster's 1913): General laws or truths from which others are derived; primary sources of action; fundamental elements or rules.
The gap matters because ordinary usage treats "principles" as aspirational or moral — things one acts in accordance with. Legal usage is more structural: principles are jurisprudential load-bearing elements, not personal commitments. When a historical legal source invokes "principles of law," it signals doctrinal architecture, not ethical orientation. Researchers conflating the two senses will misread the authority being invoked.
Common Confusion
PRINCIPLES vs. MAXIMS: The terms are closely related and sometimes used interchangeably in historical sources. Maxims are a subset — typically aphoristic, received formulations ("equity regards as done that which ought to be done"). Principles are the broader category, encompassing both maxims and non-aphoristic foundational doctrines. Bouvier treats universal principles as equivalent to axioms or maxims; Black's treats principles as the genus from which maxims may derive. Researchers in older sources should not assume the terms are always equivalent.
PRINCIPLES vs. RULES: Modern jurisprudence (following Dworkin) draws a sharper distinction than historical legal dictionaries do. Rules apply in all-or-nothing fashion; principles apply as a dimension of weight. Historical dictionaries, however, use the terms nearly interchangeably. Researchers should not import modern theoretical precision into historical source reading without confirming which sense was operative.
Why It Matters in Research
The word "principles" functions as a header term in historical legal writing — a signal that what follows is doctrinal synthesis, not a specific rule or holding. Corpus researchers should treat it as an organizational marker with two distinct implications:
First, when a statute or judicial opinion refers to "principles and usages of law" (as in historical federal practice), it invokes a body of unwritten but judicially recognized doctrine that may not appear in any single codified source. The Rapalje entry specifically flags this construction, citing federal circuit usage. Identifying what body of doctrine was considered "principle" at a given moment requires dating the source carefully — what counted as a settled principle in 1850 may have been superseded or reversed by the time of a later opinion citing the same language.
Second, in the Law Mind corpus, "principles" appears as a structural term across substantive areas — fiduciary accounting principles, agency principles, fraud principles — each reflecting a different doctrinal cluster. Researchers working across subject areas should not assume that "principle" carries identical weight or the same level of formality in each context. Fiduciary accounting principles (now partly codified through the Uniform Fiduciary Accounting Principles) carry quasi-regulatory authority; agency principles in employment law function more as common-law defaults subject to statutory override.
Historical trap: Bouvier's use of "constituent parts" language (citing 8 Term Rep. 107) refers to principles as the essence of a legal body or doctrine — a usage closer to scientific or philosophical discourse than to modern legal vocabulary. Researchers encountering this framing in 19th-century sources should not read it as metaphorical; it reflects the period's tendency to treat law as a quasi-empirical system with discoverable fundamental truths.
Historical Dictionary Support
Black's Law Dictionary (1st and 2nd editions) give identical definitions, treating principles as both foundational doctrines and settled rules of action or determination. The formulation is deliberately broad — capturing both the axiomatic and the procedural senses without distinguishing them.
Bouvier adds the epistemological dimension most explicitly: principles are truths that cannot be proved or contradicted except by propositions still clearer. This frames legal principles on the model of Euclidean axioms — not argued into existence but recognized. Bouvier also invokes the idea of principles as constitutive elements of a legal body, a sense that rarely appears in later dictionaries.
Rapalje & Lawrence, consistent with their practice, cross-references adjacent statutory constructions ("principles and usages of law," "print," "printed and published") without elaborating doctrine. The fragment suggests the entry was part of a larger alphabetical sequence and is incomplete as preserved, but the statutory construction cross-references are useful for corpus researchers tracing how courts of the period interpreted similar language.
All three historical sources agree on the axiomatic core. None engages with the rules/principles distinction that becomes central to late 20th-century jurisprudence. Researchers should not expect historical dictionary support for that theoretical distinction.
Encyclopedia Cross-Reference
Fiduciary Accounting — Principles, Standards, and the Uniform Fiduciary Accounting Principles (The Law Mind Trusts, Estates & Probate Encyclopedia)
Agency Principles in the Employment Relationship (The Law Mind Employment & Labor Law Encyclopedia)
Fraud — General Principles and Elements (The Law Mind Criminal Law Encyclopedia)