Fide-Jussor

One who becomes security for the debt of another, promising to pay it in case the principal does not do so.

He differs from co-obligor in that the latter is equally bound to a debtor with his principal, while the former is not liable till the principal has failed to fulfill his engagement.

The obligation of the fide-jussor was an accessory contract for, if the principal obligation was not previously contracted, his engagement then took the name of mandate.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.