Definition
LOCI is the Latin plural of locus (place) and appears in Anglo-American legal usage almost exclusively as a component of compound Latin maxims governing which jurisdiction's law applies to a legal dispute or transaction. Standing alone, the word simply means "of the place" or "of the places," but its legal significance lies entirely in the phrases it anchors:
1. Lex loci — "the law of the place." The foundational conflict-of-laws principle directing courts to apply the law of the jurisdiction with the most relevant connection to the matter in dispute. In its classical formulation, this meant applying the law of the place where a contract was made, where a tort occurred, or where property was situated, without further inquiry.
2. Lex loci contractus — the law of the place where a contract was made (or, in some formulations, where it is to be performed). Historically the dominant rule for contract choice-of-law questions in American courts.
3. Lex loci delicti — the law of the place where the wrong (tort) was committed. The classical rule for tort choice-of-law, largely supplanted in modern American practice by interest-balancing and most-significant-relationship tests.
4. Lex loci rei sitae (also lex rei sitae or lex situs) — the law of the place where property is situated. Still the dominant rule for questions involving title to real property.
5. Lex loci celebrationis — the law of the place where a marriage was celebrated. Historically used to determine the validity of a marriage.
Common Language
Modern common usage (Wiktionary): Listed as an alternative form of "loco," meaning locomotive (informal, chiefly transportation contexts).
Historical common usage: Not listed as a common English word; locus appears in Webster's 1913 as a Latin borrowing meaning "place," used in mathematics and surveying to describe a set of points satisfying a given condition.
The common English word "loco" and the mathematical term "locus" share the Latin root but have no bearing on legal meaning. A researcher encountering loci in a legal source should read it as shorthand for one of the lex loci compounds above. The word alone, stripped of its companion terms, carries no independent legal rule.
Common Confusion
LOCI is routinely confused with LOCUS in legal writing because American and English courts used both forms interchangeably in older opinions. Locus is the singular nominative form; loci is plural or genitive (possessive). The phrases lex loci and lex loci contractus use the genitive singular — "the law of the place" — not a true plural. Researchers should not treat loci as meaning "multiple places" when reading these maxims; the genitive construction is grammatical Latin for possession, not enumeration. Separately, lex loci (the classical vested-rights approach) should not be confused with the modern most-significant-relationship test adopted by the Restatement (Second) of Conflict of Laws; the two lead to different outcomes and reflect competing philosophical frameworks.
Why It Matters in Research
Loci appears in American legal sources primarily as the genitive element of conflict-of-laws maxims, and its meaning is inseparable from whichever compound phrase surrounds it. Researchers face two practical traps:
First, historical instability of the lex loci rules. Nineteenth- and early twentieth-century American cases applied lex loci contractus and lex loci delicti as near-absolute territorial rules derived from Joseph Story's Commentaries on the Conflict of Laws and later systematized in the First Restatement of Conflict of Laws (1934). These rules were progressively abandoned through the mid-twentieth century. A researcher reading pre-1960 cases will encounter lex loci applied rigidly; post-1970 cases from most jurisdictions will apply interest-analysis or significant-relationship tests instead. The same phrase produces different analytical frameworks depending on the era of the source.
Second, the real property exception persists. While lex loci delicti and lex loci contractus have been displaced in most American jurisdictions, lex rei sitae (the property-specific variant) remains robust for questions of title, conveyancing, and succession of real property. Bouvier's materials on foreign contract enforcement illustrate this: courts applying equitable jurisdiction would enforce a foreign contract for the conveyance of land by personal decree, but only where the contract was not repugnant to the lex rei sitae of the forum. This distinction between in personam jurisdiction over the parties and the lex rei sitae governing the land itself is a recurring complexity in historical equity practice.
Researchers working in private international law, multistate litigation, or historical conveyancing disputes should map every loci compound they encounter to its specific doctrinal context before generalizing.
Historical Dictionary Support
Bouvier's Law Dictionary does not provide a standalone entry for loci, which reflects standard practice: the word is treated as a grammatical component of compound maxims rather than an independent legal term. Bouvier's materials address the underlying doctrine through entries on lex loci contractus and related conflict-of-laws principles.
The passages preserved in the source material confirm the classical equity rule: a contract for conveyance of land, valid by the lex fori (law of the forum), could be enforced through personal process even where the land lay in a foreign jurisdiction, provided the conveyance demanded would not violate the lex rei sitae of that jurisdiction. The cases cited (Paige, Ch. and Wythe) reflect early nineteenth-century American equity practice and the influence of Story's treatise framework. Bouvier is reliable on the classical rules but does not capture the twentieth-century doctrinal shift away from strict territorial analysis.
Jurisdictional Note
The lex loci rules survive in different forms across jurisdictions. A majority of American states have moved to the Restatement (Second) most-significant-relationship test or interest-analysis for contracts and torts. Louisiana applies a civil-law-derived approach reflecting its mixed legal system. England and the EU apply distinct choice-of-law frameworks (Rome I for contracts, Rome II for torts) that use loci terminology in scholarly commentary but not in operative statutory text. Researchers should not assume that a rule labeled lex loci in one jurisdiction operates identically in another.
Encyclopedia Cross-Reference
Law Mind Encyclopedia: CONFLICT OF LAWS; LEX LOCI; CHOICE OF LAW