Definition
Latin: "at the instance of." A procedural phrase indicating that a legal action, proceeding, or order was initiated or requested at the demand or solicitation of a particular party, rather than by the court's own motion or by operation of law. Most commonly appears in the extended form ad instantiam partis, meaning "at the instance of a party."
Why It Matters in Research
Researchers encounter ad instantiam primarily in older English and early American case reports and treatises, where it appears as a shorthand notation in procedural recitals. Its significance is not substantive but structural: the phrase identifies who triggered a proceeding, which can bear on questions of standing, waiver, and party responsibility for costs or outcomes.
When reading historical reports, ad instantiam signals a distinction that modern procedure handles through explicit party designations in captions and motions. In archaic pleading, the phrase could appear without the party's name attached, requiring the researcher to look backward in the record to identify the moving party. Misreading the phrase as descriptive of the court's own action — rather than a party's instigation — can distort understanding of how a case was initiated.
The phrase also appears in ecclesiastical and admiralty contexts, where courts historically distinguished between proceedings brought at a party's instance and those brought ex officio (by the court or official on its own authority). That distinction carried real procedural consequences in those jurisdictions, affecting everything from burden of proof to the rules governing compurgation. Researchers working in pre-19th-century admiralty or ecclesiastical records should be alert to this usage.
No meaningful jurisdictional variation exists in current American practice; the phrase is vestigial in modern legal writing and appears almost exclusively in historical sources and quotations from older authorities.
Historical Dictionary Support
The historical dictionaries are in full agreement on the core meaning: "at the instance of." Black's (both editions) and Burrill share identical language and cite the same two authorities — 2 Mod. 44 (a volume of Modern Reports from English common law courts) and Hale's History of the Common Law, page 28. Bouvier's entry is brief to the point of being perfunctory, offering only the translation before pivoting immediately to define the adjacent term ad interim, suggesting the editors viewed ad instantiam as self-explanatory and uncontroversial.
None of the historical dictionaries explain the procedural significance of the phrase or its use in distinguishing party-initiated from court-initiated proceedings — an omission that leaves researchers without the context needed to apply the term accurately in archival work. Burrill, characteristically, is the most complete of the four, matching Black's language precisely while preserving the Latin citation form.
The references to 2 Mod. 44 and Hale's Common Law are genuine anchors in the historical record. Matthew Hale's History of the Common Law of England was a foundational treatise, and the Modern Reports citation reflects standard 17th- and 18th-century English case reporting practice.