Un supuesto de "indebiti solutio" del "fideiussor" en d. 12,6,47 (celsus, 6 "dig.")

This study analyses Celso's legal reasoning as to an assumption laid down in D. 12,6,47 regarding the determination of the ways to enforce the right to reimbursement to the fideiussor of an undue payment made by him, based on the power granted by the main debtor. To do this, the connotations of the Roman bail within the scope of the main issue will be determined; then some remarks regarding the ways that Celso consider to be correct to enforce the right in favor of the solvens, and thus to achieve the restoration of the aequitas, will be set forth. In this particular case, these ways are identified with the procedural instruments of the condictio indebiti and the actio mandati contraria.