Definition
Latin. The Roman legal concept underlying the English doctrine of equity. In its broadest sense, equitas denotes fairness, justice, and the idea that legal outcomes should conform to what is right rather than merely what the strict letter of the law commands. In Western legal tradition, equitas served as the philosophical and doctrinal ancestor of equity jurisprudence — the body of law developed in English Chancery courts to correct the rigidities and injustices of the common law.
Equitas is not itself a cause of action or a remedy. It is a foundational concept: the principle that law, if applied without tempering judgment, may produce unjust results, and that a parallel system of conscience-based relief is therefore necessary and legitimate.
The maxim most associated with the term — equitas sequitur legem, "equity follows the law" — captures the relationship between equitas and positive law. Equity does not override law for its own sake; it operates within legal structure while correcting its excesses. Where the common law provided no remedy, equity stepped in, but it did so by analogy to legal principles rather than by wholesale substitution of its own rules.
Common Confusion
EQUITAS vs. AEQUITAS: Roman legal texts use both forms. Aequitas is the more classical spelling found in Cicero and the Digest; equitas appears in later Latin usage and in legal dictionaries of the common law tradition. The terms are functionally synonymous in the legal research context, but researchers working in Roman law sources should expect aequitas, while common law dictionaries and English legal writing tend toward equitas.
EQUITAS vs. EQUITY: Equitas is the Latin source concept; equity is its common law institutional successor. The two share philosophical content but are not interchangeable in research. Equity, as developed in English Chancery, became a body of positive doctrine — specific remedies, doctrines, and procedures. Equitas remains a theoretical premise. Citing equitas in a common law argument is citing the philosophical root, not the institutional branch.
Why It Matters in Research
Researchers encounter equitas primarily in three contexts: historical legal dictionaries, Roman law scholarship, and jurisprudential writing about the foundations of equity jurisdiction.
In historical common law dictionaries, equitas appears almost exclusively as a definitional entry cross-referencing equity. It functions as a gateway term rather than a standalone doctrine. Anderson's entry is representative: the substance is in the cross-reference to EQUITY, and the Latin is treated as a label rather than a concept requiring independent analysis.
The maxim equitas sequitur legem appears frequently in Chancery-era literature and in early American equity decisions. Researchers tracing the doctrinal history of equity jurisdiction will find this maxim used both to justify equitable intervention (equity fills the gaps law leaves) and to cabin it (equity does not displace law where law speaks clearly). The same phrase, in other words, was wielded by both expansionists and restrictionists of equitable relief. Context and period matter enormously.
Researchers working in civil law or comparative law traditions will find a richer and more independent treatment of equitas/aequitas. In Roman law, the concept had genuine operative significance — it influenced the praetor's edict and the development of the ius gentium. That doctrinal weight does not automatically carry into common law sources, where equitas is largely honorific.
A trap in historical sources: older English legal writers sometimes use equitas and equity interchangeably without signaling which they mean. When a 17th or 18th century treatise invokes equitas, determine whether the author is making a philosophical point about fairness or a doctrinal point about Chancery jurisdiction. The distinction affects how the passage should be read and cited.
Historical Dictionary Support
Anderson's Dictionary of Law provides the representative entry for equitas in the common law dictionary tradition: a brief Latin gloss followed by the maxim equitas sequitur legem and an immediate cross-reference to EQUITY. This treatment is consistent across most English-language legal dictionaries of the 19th and early 20th centuries. The term is present but thin — the lexicographers recognized it as foundational vocabulary without treating it as doctrine requiring extended analysis.
What the historical dictionaries largely omit is the Roman law context. The concept of aequitas in the Digest and in Cicero's writings — where it functions as a standard of judgment, a basis for the praetor's discretion, and a check on the literalism of the ius civile — receives almost no treatment in common law dictionary entries. Researchers should not rely on common law legal dictionaries for substantive guidance on equitas in the Roman or civilian sense. That literature requires separate consultation.
The maxim equitas sequitur legem itself has a more contested history than the dictionary entries suggest. It does not originate as a formal Roman maxim; it crystallized in English Chancery jurisprudence as a way of describing the relationship between equity and common law. Its invocation in 19th century American cases often reflects inherited English usage rather than independent analysis of Roman sources.
Jurisdictional Note
As a Latin source concept rather than a doctrine, equitas has no jurisdiction-specific application. Its relevance in American legal research is almost entirely historical and jurisprudential. Researchers in civil law jurisdictions (Louisiana, Quebec, mixed systems) may encounter more direct engagement with aequitas as an operative principle in civilian codifications and commentary.
Encyclopedia Cross-Reference
Law Mind Encyclopedia — Equity
Law Mind Encyclopedia — Roman Law Foundations
Law Mind Encyclopedia — Chancery Jurisdiction