Definition
A pactum constitutae pecuniae (also rendered pactum constitute pecuniae or simply constitutum) is a civil law agreement by which a debtor promises a creditor to pay on a specified day or at a specified time — either a debt already owed, or a debt owed by a third party. The pact does not extinguish the underlying obligation; it adds a new, enforceable promise alongside the original duty.
Two operative forms are recognized in the classical civil law authorities:
1. Constitutum debiti proprii — A promise by a debtor to pay his own creditor. The pre-existing debt remains intact, and the new promise creates an additional obligation. The creditor thus holds two grounds of action: the original cause and the pact.
2. Constitutum debiti alieni — A promise by a third party to pay another person's debt to that person's creditor. This form functions analogously to a suretyship or guarantee, creating personal liability in the promisor without releasing the original debtor.
The essential character of the pactum is temporal specificity: the agreement must fix a day or time certain. A bare promise to pay, untethered to any appointed time, would not ripen into a constitutum under classical doctrine.
Common Confusion
The pactum constitutae pecuniae is sometimes loosely equated with novation, but the two are structurally distinct. Novation (novatio) extinguishes the prior obligation by substituting a new one. The constitutum leaves the original obligation standing; it superadds a new cause of action without destroying the first. A creditor after novation has one claim; a creditor after constitutum has two. Researchers encountering these terms in civil law treatises or Louisiana and Quebec sources should not treat them as interchangeable.
Why It Matters in Research
This term appears almost exclusively in civil law contexts — Roman law, canon law, and the mixed jurisdictions that inherited Roman private law traditions (Louisiana, Quebec, Scotland, and their historical predecessors). Common law researchers encountering it will do so in comparative treatises, conflict-of-laws discussions, or historical scholarship on the civil law roots of modern guarantee and surety doctrine.
The term is a research marker. When it appears in a historical document, it signals that the author is working within, or at least citing to, a Roman or civil law framework. Common law writers occasionally deployed the term to distinguish civil law suretyship arrangements from common law guaranty, so its appearance in an English-language treatise may signal a comparative argument rather than a claim that the doctrine actually governs the dispute at hand.
Researchers in Louisiana legal history should note that the constitutum informed early Louisiana Civil Code drafting on suretyship and promise to pay, making it relevant to tracing how modern Louisiana obligations articles acquired their structure. The civil law/common law boundary matters here: the same transactional arrangement might be analyzed through constitutum logic in civilian courts and through consideration-based contract or surety doctrine in common law courts.
Because the doctrine creates an additive obligation rather than a substituted one, it also surfaces in historical discussions of debt collection, delays of payment, and the legal status of time-certain payment promises — areas relevant to commercial law history research.
Historical Dictionary Support
Bouvier and Rapalje & Lawrence are in substantial agreement on core doctrine, though Bouvier provides more structural precision. Both identify the pact as a promise to pay on an appointed day; both treat it as generating a new obligation without destroying the former. Bouvier's articulation — "there arises a new obligation, which does not destroy the former by which he was already bound" — is the cleaner statement of the additive character of the agreement and is the formulation most useful for distinguishing the constitutum from novation.
Neither source develops the debiti alieni form at length in the excerpted passages, though classical Roman law and the broader Bouvier entries elsewhere treat it as equally recognized. Researchers relying solely on these dictionary entries should consult the Digest (D. 13.5) and Justinian's Institutes directly for the full doctrinal framework, including the praetorian action (actio de pecunia constituta) that enforced the pact.
Wharton's Law Lexicon, cited by Rapalje & Lawrence, follows the same summary approach. None of these dictionaries address the gradual absorption of constitutum principles into modern suretyship doctrine — a gap that matters for anyone tracing doctrinal lineage forward from Roman sources into nineteenth-century civil law codifications.
Jurisdictional Note
The pactum constitutae pecuniae is a doctrine of Roman and civil law with no direct common law counterpart. It remains analytically relevant in Louisiana, Quebec, and other mixed jurisdictions, and in historical scholarship on suretyship and guarantee across civil law systems. Common law jurisdictions address similar transactional problems through guaranty, indemnity, and the law of consideration rather than through this doctrine.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia — Roman Law Foundations of Contract; Suretyship and Guarantee: Historical Development; Civil Law Obligations in Mixed Jurisdictions