Definition
An action in Roman civil law brought by the borrower against the lender to compel the lender's performance of obligations arising from a contract of loan for use (commodatum). Where the primary action — the actio commodati directa — ran in favor of the lender to recover the thing lent, the actio commodati contraria ran in the opposite direction: it gave the borrower a remedy when the lender had failed to fulfill duties owed under the same contract, such as reimbursing the borrower for extraordinary expenses incurred in preserving the loaned object, or compensating for harm caused by a defect in the thing lent that the lender knew about and failed to disclose.
The term reflects the standard Roman practice of pairing actions: a directa action enforced the primary, intended obligation of a contract, while the contraria action enforced secondary or incidental obligations running back toward the other party.
Common Confusion
ACTIO COMMODATI CONTRARIA vs. ACTIO COMMODATI DIRECTA: These two actions arise from the same contract but belong to opposite parties. The directa is the lender's action to recover the loaned item at the end of the loan period — the central purpose of commodatum. The contraria is the borrower's action, available only when the lender has incurred an obligation to the borrower as a side-effect of the arrangement. Researchers encountering either term in a source should confirm which party is the plaintiff before drawing conclusions about the substance of the dispute.
ACTIO COMMODATI CONTRARIA vs. CONDICTIO: Both could theoretically benefit a borrower in a commodatum context, but they are distinct instruments. The condictio was a personal action to recover a specific thing or sum based on unjust enrichment or an obligation to restore; the actio commodati contraria was grounded in the contractual relationship of the loan for use itself. The distinction matters when reading Roman law commentary because writers do not always specify which remedy they are discussing.
Why It Matters in Research
This term appears almost exclusively in sources dealing with Roman law or in early modern common law treatises that drew on civilian doctrine to analyze gratuitous bailments. Researchers working in English legal history will encounter commodatum analysis primarily in writers like Bracton and in later equity materials, though English common law never fully adopted the Roman actio framework by name. The pairing of directa and contraria actions is a structural feature of Roman obligational thinking that recurs across multiple contract types — understanding the pattern here aids comprehension of analogous paired actions elsewhere in the civil law corpus (e.g., actio mandati contraria, actio negotiorum gestorum contraria).
In civilian jurisdictions and mixed legal systems (Scotland, Louisiana, South Africa, Quebec), commodatum survives as a recognized contract category and the underlying logic of the contraria action — that a gratuitous lender may owe duties back to the borrower — remains doctrinally live, even if the Roman action name itself does not appear in modern statutes.
When searching historical sources, note that spelling varies considerably: commodati, commodatii, and the ligature rendering in older print (АСТІО СОMMODATI, as reproduced in some Black's editions) can interfere with keyword searches in digitized databases. Search on the root commodat- rather than the full phrase.
Historical Dictionary Support
Black's Law Dictionary provides a compact entry that accurately identifies the action as civilian in origin and correctly pairs it with its counterpart, the actio commodati directa, citing Pothier's Prêt à Usage (nos. 65, 68, and 75) for both. Pothier's treatise on the loan for use remains the standard secondary authority for the civilian framework on commodatum and is the source Black's relies on throughout this cluster of entries.
Black's definition is accurate but minimal. It identifies the borrower as plaintiff and compellment of contract execution as the object, but does not enumerate the specific lender obligations that could give rise to the action — most importantly, the lender's duty to compensate for harm caused by undisclosed defects in the thing lent (a point Pothier addresses directly). Researchers should consult Pothier directly for doctrinal depth, as Black's entry functions more as a pointer than a full explanation. No significant divergence exists among the historical dictionaries on the basic identification of this action; the term is narrow enough that sources agree on its essentials.
Jurisdictional Note
The actio commodati contraria has no direct equivalent by name in Anglo-American common law. Its functional content — a borrower's right to recover from a lender for losses caused by undisclosed defects — survives in modern common law through the law of gratuitous bailment and products liability, not through the Roman action framework. In civil law jurisdictions that codified Roman law, the obligations underlying the contraria action typically appear in the commodatum articles of the relevant civil code rather than as a distinct named action.