Bellum iustum tra rito e iustae causae belli

After a survey of the relevant works on the subject, the article studies the prerequisites of the bellum iustum in Rome. Two distinct issues are usually considered to be involved: a formal one, i.e. the fetial ritual for the declaration of war; and a substantial one, i.e. a just ground to declare war (iusta causa belli). Some scholars have argued that both were relevant, though on different plans, whereas others have given importance to only one of the two. It is here maintained that in archaic law the ritual and the just ground were indistinct aspects of the same claim brought by the Roman people; and that only in the late Republic, after Cicero’s treatment of the subject and the likely influence of the Greek thought, the two profiles became structurally distinct, although functionally linked.