Definition
Jus precarium (Latin: "precarious right") is a concept originating in Roman civil law describing a right of use or enjoyment over a thing that is held entirely at the sufferance of another — granted by request or favor, with no legal remedy to enforce or protect it. The holder of a jus precarium could not compel its continuation or recover the thing through legal action; the only available recourse was entreaty or petition to the grantor.
The defining characteristic is the absence of legal enforceability. The right exists in fact but not in law: it persists only so long as the grantor tolerates it, and it terminates the moment the grantor withdraws consent. This stands in sharp contrast to a legal property right or even an equitable interest, both of which carry enforceable remedies.
The concept passed from Roman civil law into the common law discourse primarily through treatises on property and equity, where it served as a reference point for distinguishing enforceable interests from gratuitous, revocable permissions — a distinction that matters in contexts ranging from licenses to early analysis of Uses.
Common Confusion
Jus precarium is sometimes loosely equated with a license or a bare permission in modern property law. The overlap is real but the terms are not identical. A modern license is understood within a doctrinal framework that includes questions of irrevocability, estoppel, and consideration; jus precarium, as used in the historical sources, describes a condition prior to or outside that framework — a grant that, by definition, generates no actionable right whatsoever, not merely a revocable one. Similarly, jus precarium should not be confused with a tenancy at will, which, though terminable, carries recognized legal incidents and remedies during its operation. Jus precarium carries none.
Why It Matters in Research
Researchers encounter jus precarium most often in three contexts: treatise analysis of Roman property law, early equity scholarship on the nature of Uses, and historical commentary on the boundary between license and property.
In early equity sources, the term appears in discussions of whether a cestui que use held anything more than a jus precarium before equity developed enforceable remedies — making the term a conceptual marker for the pre-enforcement period of equitable doctrine. Bacon's Reading on Uses, cited by Burrill, is a key source here.
The phrase also appears in judicial opinions working through foundational property questions. Burrill cites Chancellor Cowen's usage in New York Hill's Reports, signaling that the term had some active life in early American jurisprudence, not merely antiquarian citation.
The principal research trap is treating jus precarium as a static technical term with a fixed modern equivalent. It is better understood as a conceptual anchor — a Roman baseline against which common law and equity courts measured the strength of various claimed interests. Its appearance in a source is frequently a signal that the author is distinguishing legally cognizable rights from those resting purely on goodwill.
When the term appears in historical sources alongside jus presentationis (cited in Rapalje & Lawrence), the discussion is likely turning on the question of what remedy, if any, accompanies a given right — a structural question about the architecture of the right rather than its substance.
Historical Dictionary Support
The historical dictionaries agree on the core proposition: jus precarium denotes a civil law right for which no legal remedy existed, enforced only by entreaty (prece) or request. All four sources trace the concept to 2 Bl. Comm. 328, anchoring the term in Blackstone's treatment of property.
Burrill provides the most complete gloss, explicitly unpacking the Latin root (prece, meaning "entreaty") and making clear that the absence of remedy is not incidental but definitional — the right is precarious precisely because it cannot be compelled. Burrill also uniquely supplies the Bacon and New York judicial citations, making his entry the most useful for researchers tracing the term's active doctrinal use rather than its theoretical genealogy.
Black's first and second editions are functionally identical on this term, both relying on the Blackstone citation without independent elaboration.
Rapalje & Lawrence is the outlier. Their entry pairs jus precarium with jus presentationis in a manner that is editorially compressed and, as printed, partially garbled — the entry appears to contain textual fragments from an adjacent entry on rights in a wife's estate (referencing Snell's Equity and letters of administration), suggesting a typographical or editorial corruption in the source. Researchers should treat the Rapalje & Lawrence entry with caution and cross-check against Burrill for this term.
None of the historical dictionaries address the term's trajectory after equity courts began enforcing what had previously been mere precarious interests — a significant doctrinal development that falls outside their definitional scope but is essential context for understanding why the term appears in equity treatises.
Jurisdictional Note
Jus precarium is a civil law concept with no direct equivalent in Anglo-American statutory or common law. Its significance in common law jurisdictions is historical and doctrinal rather than operative — it appears in treatises, judicial opinions drawing on Roman foundations, and academic commentary, but not as an enforceable legal category. Civil law jurisdictions (including Louisiana and Quebec in North American contexts) may retain closer functional analogs through their Roman law inheritance.
Encyclopedia Cross-Reference
Law Mind Encyclopedia — Roman Property Law
Law Mind Encyclopedia — Precarium
Law Mind Encyclopedia — Uses and Equitable Interests