Definition
A Latin phrase meaning "for this" or "for this specific purpose." In legal usage, ad hoc describes something created, appointed, or convened for a single, defined purpose — not as part of a standing structure and not intended to carry forward beyond the immediate need.
The phrase appears most often in the following legal contexts:
1. Ad hoc appointment: A judge, guardian, curator, or attorney appointed solely to handle a specific matter or proceeding, whose authority does not extend beyond that appointment. A guardian ad litem is the most frequently encountered example.
2. Ad hoc tribunal or committee: A body convened to address a particular dispute, investigation, or question, then dissolved. Contrasted with permanent courts or standing committees.
3. Ad hoc arbitration: Arbitration proceedings structured by the parties themselves for a specific dispute, as distinguished from institutional arbitration administered under permanent rules by an established body.
Common Language
Modern common usage (Wiktionary): "For a particular purpose"; also used loosely to mean improvised or created on the spur of the moment; in philosophy of science, used to describe a hypothesis inserted to rescue a theory without generating new predictions.
Historical common usage (Webster's 1913): Webster's 1913 does not carry a separate entry for ad hoc, reflecting its status at that time as a Latin phrase used primarily by lawyers and academics rather than in general circulation.
The gap worth noting: In modern common speech, ad hoc has acquired a mildly negative coloring — implying improvisation, lack of planning, or a patch applied to a broken system. In legal usage the term is neutral and often formally precise. An ad hoc appointment is not an improvised one; it is a defined, purposeful arrangement with specific legal authority and limits. Researchers reading legal documents should not import the common connotation of sloppiness or expediency into legal contexts where the term simply means purpose-specific.
Common Confusion
Ad hoc is sometimes loosely conflated with pro hac vice. They are related but distinct. Pro hac vice ("for this occasion") describes an attorney admitted to practice in a jurisdiction solely for a particular case, without being generally admitted to the bar there. Ad hoc describes the nature or scope of an appointment, role, or body — not the mechanism of temporary bar admission. A guardian ad hoc and an attorney pro hac vice both serve limited purposes, but the phrases are not interchangeable.
Why It Matters in Research
The phrase appears across virtually every practice area and procedural context, which means corpus researchers encounter it in widely varying settings that require different follow-through.
The guardian ad litem context is the most document-dense. Historical and modern case law involving minors, incompetent parties, or conflict-of-interest situations will frequently reference appointments ad hoc or guardians ad litem. The two phrases are used interchangeably in some jurisdictions and distinctly in others — Louisiana sources in particular use "curator ad hoc" and "attorney ad hoc" in ways that do not map cleanly onto how common-law jurisdictions use guardian ad litem. The Black's citations (Sallier v. Rosteet; Bienvenu v. Insurance Co.) are Louisiana cases, which signals that the Black's definition reflects civilian practice. Researchers applying that definition in common-law contexts should verify whether the same term carries the same scope.
In international arbitration research, "ad hoc arbitration" is a term of art with significant procedural implications — governing which rules apply (often the UNCITRAL Arbitration Rules by agreement) and what institutional support, if any, exists. The phrase does not appear in this sense in the historical dictionaries, which reflects how recently arbitration developed into its current form. Researchers in the Law Mind corpus working on arbitration topics should treat the historical dictionary treatment of ad hoc as incomplete for that context.
In constitutional and administrative law contexts, ad hoc decision-making has doctrinal significance — courts reviewing agency action or equal protection claims may ask whether a decision was made on principled grounds or merely ad hoc, and that distinction carries legal weight that the dictionary definition alone does not convey.
Historical Dictionary Support
Burrill provides the most useful historical treatment, anchoring the phrase in its Latin roots (to this; for this) and noting its use in Bracton in the expression ad hoc facit — meaning "this supports the present point" or "this goes to establish the principle." That usage reflects an evidentiary or argumentative function: a rule, authority, or text is cited as going to, or favoring, the matter at hand. This is historically distinct from the modern sense of a purpose-specific appointment, though both share the core meaning of relevance or application to a particular thing.
Black's is the most practically useful of the three, defining the term in its appointment context and grounding it in specific cases. Bouvier's entry for ad hoc is unhelpfully absent — the source material provided under Bouvier references ad inquirendum, not ad hoc, suggesting either an indexing gap or that Bouvier did not treat the phrase as a standalone entry of significance.
None of the historical dictionaries address ad hoc arbitration, ad hoc committees, or administrative law applications — all of which are now primary contexts for the phrase in legal research.
Jurisdictional Note
Louisiana's civil law tradition gives ad hoc appointments a more formally defined procedural role than is typical in common-law states. The terms "curator ad hoc" and "attorney ad hoc" appear in Louisiana procedural law with specific statutory grounding. Researchers working across jurisdictions should not assume that Louisiana cases define the term's scope for other states.
Encyclopedia Cross-Reference
The Law Mind Family Law Encyclopedia — Child Custody: Custody Evaluations and Guardian ad Litem (family_73). The guardian ad litem, one of the most frequently encountered ad hoc appointments, is addressed in depth there.