Definition
Latin: "at the suit of." A Latin phrase used in legal practice and case indexing to indicate that the named party is the defendant, not the plaintiff. When a case caption is written with the defendant's name first, ad sectam — abbreviated as ads. — signals the inversion. In the form "B. ads. A.," B is the defendant in an action brought by A. This is the logical equivalent of the more familiar "A. v. B." written in reverse order.
Ad sectam appears most often in older court records, pleading papers, and the indexes to early American and English law reports. It was used when practical convention required the defendant's name to lead — for instance, when the defendant was the filing party on a particular paper.
Common Confusion
Ad sectam (ads.) is occasionally confused with the abbreviation for "advertisement" or similar shorthand in non-legal contexts. Within legal research, the chief confusion is between ads. and v. (versus): both connect two party names in a case caption, but ads. reverses the standard plaintiff-first order. A case styled "Smith ads. Jones" means Jones sued Smith — the opposite of what a reader accustomed to "Jones v. Smith" might assume. Failing to recognize the inversion can cause a researcher to misidentify which party brought the action.
Why It Matters in Research
The phrase is effectively obsolete in modern American practice, but researchers working in historical sources will encounter it regularly in two contexts: case indexes and pleading files.
In older American reports — particularly those from the late eighteenth and early nineteenth centuries — some indexes organized cases by defendant name and used ads. to flag that inversion. A researcher scanning an index for a party's litigation history must recognize that an ads. entry places the defendant first; overlooking this convention can cause a case to be missed entirely, or a party's role to be misread.
In pleading files, ads. appears in paper captions filed by defendants. Burrill notes its retention in entitling papers even after it fell from common use in published reports, meaning the abbreviation may surface in manuscript court records and docket books long after it disappeared from print indexes.
The phrase also carries variant forms worth knowing: ad sectam querentis means "at the suit of the plaintiff," and ad nullius sectam means "at the suit of no one" — a phrase with significance in older writs describing actions that could be brought without a private complainant. Researchers encountering these extended forms in Bracton-era or early common law materials should not treat them as merely stylistic variants; the full phrase encodes substantive procedural information about who initiated the action and in what capacity.
Modern electronic databases have largely absorbed the problem by normalizing party names regardless of filing convention, but PDF and image-based sources — digitized early reporters, chancery records, colonial court files — preserve the original caption order without normalization. In those sources, ads. remains an active research hazard.
Historical Dictionary Support
All four source dictionaries agree on the core definition: ad sectam means "at the suit of" and functions as a defendant-first caption marker abbreviated to ads. The sources converge without meaningful disagreement on this point.
Burrill is the most useful of the four for historical depth. He traces the phrase to Bracton and the Registrum Omnium Brevium, and preserves the variant forms (ad sectam querentis, ad nullius sectam) that the other dictionaries omit. His note that the abbreviation was "still retained in practice, in entitling papers" at the time of writing confirms that ads. persisted in live use even as it faded from published indexes.
Bouvier adds the practical observation that the term "has become pretty much disused" and locates its primary survival in "indexes to cases decided in some of our older American books of reports" — useful confirmation of where researchers should expect to find it.
Black's (both editions) gives the clean modern summary without historical elaboration, sufficient for identification but not for understanding the term's procedural context in earlier sources.
None of the historical dictionaries address the digital research implications — the normalization problem in electronic databases versus image-based sources — which is the most practically significant gap for contemporary researchers.