Fide jussor

Definition of Fide jussor

In Roman law, a guarantor; one who becomes responsible for the payment of another’s debt, by a stipulation which binds him to discharge it if the principal debtor fails to do so. 3 Bl.Comm. 108. He differs from a co-obligor in this, that the latter is equally bound to a debtor, with his principal, while the former is not liable till the principal has failed to fulfil 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. The sureties taken on the arrest of a defendant, in the court of admiralty, were formerly denominated "fide jussors.” 3 Bl.Comm. 108.

That's the definition of Fide jussor in Black's Law Dictionary 6th Edition. Courtesy of