M. Tullius Cicero Pro Q. Roscio Comoedo 10

1. Professor Long's explanation of the difference here laid down is little more than a translation of and comment on this passage. He says, “The following is the distinction between arbitrium and judicium according to Cicero ( Pro Rosc. Com. 4 ). In a judicium the demand was of a certain or definite amount, pecuniae certae).; in an arbitrium the amount was not determined ( incertae.) In a judicium the plaintiff obtained all that he claimed or nothing, as the words of the formula show, “ si paret H. S. 1000 dari oportere.” (Compare Gaius, iv. 50. ) The corresponding words in the formula arbitraria were “ Quantum aequius melius, id dari”; and their equivalents were “ ex fide bona; ut inter bonos bene agier.” (Top. 17)... If the matter was brought before a judex, properly so called, the judicium was constituted with a poena, that is per sponsionem; there was no poena when an arbiter was demanded, and the proceeding was by the formula arbitraria. The proceeding by the sponsio then was the strict one, “ Angustissima formula sponsionis,” ( Cic. pro Rosc. Com. 14 ); that of the arbitrium was ex fide bona, and the arbiter, though he was bound by the instructions of the formula, was allowed a greater latitude by its terms. The engagement between the parties who accepted an arbiter, by which they bound themselves to abide by his arbitrium, was compromissum. ( Pro Rosc. Com. 40 ) But this term was also employed, as it appears, to express the engagement by which parties agreed to settle their differences by arbitration, without the intervention of the praetor. Smith, Dict. Ant. v. 530 v. Judex.