Definition
A Latin phrase meaning "at the cost" or "at the expense of." Used in legal instruments, writs, and pleadings to indicate which party bears the costs of a proceeding or action. The phrase appears in several variant forms across historical sources: *ad custum ejus* (at his cost), *ad custum suum vel custum tuum* (at his cost or yours), and *ad custus* (at the costs). These variants function identically in meaning, differing only in person and number to fit the grammatical context of the surrounding Latin text.
Common Confusion
Ad custum is sometimes encountered in close proximity to *ad damnum* in historical pleading documents, and researchers unfamiliar with Latin legal phrases may conflate the two. They are distinct: *ad custum* designates who bears the expense of an action or proceeding, while *ad damnum* designates the amount of injury or damages claimed by the plaintiff. The confusion is understandable because both phrases appear in writs and declarations and both address financial consequences, but they serve entirely different functions in the structure of a pleading.
Why It Matters in Research
This is a term of pure historical significance. Modern legal drafting abandoned Latin pleading conventions long ago, so *ad custum* will not appear in contemporary sources. Researchers will encounter it almost exclusively in pre-nineteenth-century English writs, chancery documents, and common law pleadings, as well as in early American materials that preserved Latin pleading forms.
The phrase matters most as a key to interpreting cost-allocation language in historical instruments. When reading a writ or declaration and identifying who was responsible for court costs or execution expenses, *ad custum* and its variants are the operative signals. Misreading or skipping these phrases can lead to misattributing cost obligations, which may affect understanding of how a proceeding was structured or what a judgment required.
The Bracton citations in Burrill (fol. 234a and fol. 328) point researchers to one of the foundational sources of English common law, *De Legibus et Consuetudinibus Angliae*. The *Registrum Omnium Brevium* (*Reg. Orig.*) citation at 279b is another standard repository of writ forms and is a useful parallel source for verifying how *ad custum* appeared in standardized pleading templates.
Researchers working in the Law Mind corpus should note that *ad custum* may appear embedded within longer Latin passages without separate indexing. Full-text search for variant spellings (*custus*, *custum*, *custis*) will capture the range of forms used across different periods and scribal traditions.
Historical Dictionary Support
The historical dictionaries converge cleanly on the definition. Black's gives the bare translation ("at the cost") with a citation to Blackstone's *Commentaries* (1 Bl. Comm. 314). Bouvier repeats the translation and the same Blackstone citation. Burrill is the most useful of the three: it supplies the Bracton references, lists the variant Latin forms with their English equivalents, and contextualizes the phrase within actual writ language. None of the three dictionaries elaborates on the procedural significance of the phrase, which is consistent with their treatment of it as a straightforward translation term rather than a term of art requiring doctrinal explanation.
Black's curious placement of a note about episcopal admission in a *quare impedit* action appears in the same dictionary vicinity as this entry and reflects editorial proximity in the original rather than any connection to *ad custum* itself. Researchers should not import that context into the meaning of this phrase.