The tradition is constituted by the norms of conduct of the gentes and the patrician familiae. The right is the foundation of the ruling class power of the patricians first, of the patrician-plebeian nobilitas then. The hegemony of the pontiffs in the juridical field is subsequently questioned by the iurisprudentia, starting from the 3rd century BC. We examine the legal value of mos and consuetudo as sources of law in Cicero. Afterwards, we evoke the crisis of tradition and the evolution of right caused by changing social and political conditions. The mos maiorum knows the maximum crisis in the late-Republican age. Cicero considers it necessary to implement a critical revision of the mos maiorum. However, the individualism present at the time of the author makes the moral and political rebirth of Rome impossible.