The Doctrine of Producto Illicito : Ownership, Accession, and the Limits of Restitution in Civil Law

A thief steals a pregnant mare. The foal born is a producto illicito relative to the thief. According to the principle nemo suam turpitudinem allegans auditur , the thief cannot claim ownership of the foal. The original owner retains a vindicatory claim over both the mare and its producto illicito (foal). If the foal has been sold, the thief is liable for unjust enrichment. 4. The "Bad Faith Possessor" Rule Most civil law systems impose strict liability on the possessor in bad faith (the producer of illicit product). Article 549 of the French Civil Code provides that "the possessor in good faith acquires the fruits." By converse implication, the possessor in bad faith does not acquire the fruits. The producto illicito must be returned to the owner or, if return is impossible, compensated for at the highest market value.

The concept of producto illicito (illicit product) arises at the intersection of property law (accession) and the principle of nemo auditur propriam turpitudinem allegans (no one can be heard to plead their own turpitude). This paper examines how civil law jurisdictions treat fruits or products generated from illegal activities or illegal contracts. While natural and industrial fruits are typically governed by the right of accession ( accessio ), illicit products pose a unique challenge: they cannot be claimed by the perpetrator of the illegality, nor can they be easily integrated into the patrimony of the state without due process. This analysis concludes that producto illicito is not a true proprietary right but a form of quasi-custodial liability, subject to confiscation without compensation. 1. Introduction In classical Roman law and modern civil codes (e.g., French, Spanish, Italian, Louisiana Civil Code), the concept of fruits ( fructus ) is fundamental. Fruits are divided into natural (produced by a thing without human intervention), industrial (produced by cultivation), and civil (rent, interest). However, when the underlying source or the act of production violates the law or public policy, the resulting product is not considered a legitimate fruit but a producto illicito .

[Generated AI Legal Studies] Date: April 14, 2026