Definition
An irregular deposit is a type of deposit in which the depositor transfers fungible property — typically money — to a custodian (such as a bank or banker) with the understanding that the custodian need not return the identical items deposited, but only an equivalent quantity of the same kind. Ownership of the deposited property passes to the custodian, who is obligated to return an equal sum or equivalent quantity on demand.
This distinguishes the irregular deposit from a regular deposit, in which the depositor retains ownership and the custodian is obligated to return the exact same property entrusted. An irregular deposit most commonly arises when a person deposits money with a bank or similar institution for safekeeping.
The concept belongs primarily to civil law doctrine and has its most developed expression in Roman law and jurisdictions that inherited the civil law tradition. In common law systems, the functional equivalent is largely absorbed into the law of debtor-creditor relationships, general banking deposits, and the law of bailment.
Common Confusion
IRREGULAR DEPOSIT vs. MUTUUM: These two concepts are closely related and are frequently conflated. Both involve the transfer of fungible property with an obligation to return an equivalent quantity rather than the identical items. The traditional distinction turns on purpose: a mutuum (loan for consumption) is made primarily for the benefit of the borrower, while an irregular deposit is made primarily for the benefit of the depositor — that is, the depositor seeks safekeeping rather than extending credit. In practice, however, a bank deposit fulfills both functions simultaneously, and many civil law jurists acknowledged that the distinction could become thin. Black's notes this difference explicitly.
IRREGULAR DEPOSIT vs. REGULAR DEPOSIT: A regular deposit (depositum) requires return of the identical property and does not transfer ownership. An irregular deposit transfers ownership and requires only equivalent return. A bag of coins sealed for return is a regular deposit; money paid into a general bank account is an irregular deposit.
Core Elements
An irregular deposit is generally understood to require:
1. Transfer of fungible property (almost always money, but historically extended to grain, oil, or other goods sold by measure or weight).
2. Transfer of ownership to the depositee, who may commingle the deposit with their own property.
3. An obligation on the depositee to return an equivalent quantity of the same kind on demand.
4. The transaction is undertaken primarily for the benefit or convenience of the depositor (as safekeeping), not primarily for the benefit of the depositee.
Why It Matters in Research
The phrase "irregular deposit" will appear with some frequency in pre-twentieth-century treatises on banking law, commercial law, and civil law, and less often in American case law. Researchers need to be alert to several navigational issues.
First, the term is primarily a civil law category. English-language common law sources rarely use it as a standalone term of art. Where you encounter it in American materials, the context is almost always borrowed doctrine — either from civilian-influenced Louisiana jurisprudence, from treatises drawing on continental sources, or from scholarly attempts to rationalize the legal nature of bank deposits. If you are researching the legal nature of bank deposits in a common law jurisdiction, the more useful native common law vocabulary is the debtor-creditor relationship arising from a general bank deposit, not irregular deposit.
Second, this doctrinal label matters for liability analysis. Because ownership passes to the depositee in an irregular deposit, the depositee's insolvency is a loss risk for the depositor — a result that differs from a regular bailment, where the property remains the bailor's. This distinction had real stakes in historical cases involving failed banks and insolvent custodians.
Third, in Louisiana and other mixed civil law jurisdictions, irregular deposit doctrine retains operative legal force and appears in codified civil law provisions. Researchers working with Louisiana materials will find the term used with doctrinal precision.
Fourth, the modern equivalent — the general bank deposit — is now governed entirely by statute and the UCC in American jurisdictions. The civilian vocabulary of irregular deposit has been displaced in practice by Article 4 of the UCC (Bank Deposits and Collections). Understanding the historical label helps researchers trace the intellectual lineage of rules that may no longer carry the name.
Historical Dictionary Support
Black's Law Dictionary provides the most useful entry among the shelf sources. It correctly identifies the irregular deposit as arising when a party confides money to another (typically a bank) who is to return not the same money but a like sum on demand, and it correctly identifies the essential distinction from the mutuum: the irregular deposit has the benefit of the depositor principally in view, while the mutuum has the benefit of the borrower in view. This formulation is consistent with the standard civil law exposition found in Pothier and later commentators.
Rapalje & Lawrence offers no substantive definition, redirecting to a general DEPOSIT entry that is not reproduced in the available excerpt. This is typical of that dictionary's treatment of subsidiary civil law concepts.
Bouvier's entry is similarly truncated in the available text, cutting off mid-redirect. Given Bouvier's general structure, the full entry likely cross-referenced the broader treatment of deposit with a note on the civil law distinction.
None of the available historical dictionary sources fully engages the doctrinal tension that occupied nineteenth-century banking law scholars: whether the irregular deposit, once the depositor-depositary relationship was reduced to a simple debtor-creditor relationship, retained any meaningful doctrinal distinction from a loan. Later treatise writers, particularly those influenced by Story's work on bailments, tended to treat the irregular deposit as simply a special case of the mutuum or as a relationship that generated debt, not a continuing property interest.
Jurisdictional Note
Louisiana recognizes irregular deposit as a substantive civil law category with specific codified rules derived from French and Roman law sources. In common law states, the concept has no independent doctrinal existence; the legal nature of a bank deposit is governed by the debtor-creditor framework and UCC Article 4. Researchers should not assume that results reached under civilian irregular deposit doctrine will translate directly into common law banking analysis.
Encyclopedia Cross-Reference
The Law Mind Contracts & Commercial Law Encyclopedia: Negotiable Instruments — Bank Deposits and Collections (UCC Article 4) [contracts_158]
The Law Mind Contracts & Commercial Law Encyclopedia: Negotiable Instruments — Types (Notes, Drafts, Checks, Certificates of Deposit) [contracts_151]