A person who has been enriched without cause at the expense of another person is bound to compensate that person. The term "without cause" is used in this context to exclude cases in which the enrichment results from a valid juridical act or the law. The remedy declared here is subsidiary and shall not be available if the law provides another remedy for the impoverishment or declares a contrary rule.
The amount of compensation due is measured by the extent to which one has been enriched or the other has been impoverished, whichever is less.
The extent of the enrichment or impoverishment is measured as of the time the suit is brought or, according to the circumstances, as of the time the judgment is rendered.
La. C.C. § 2298