By adopting Aristotelian doctrines, reviewed in the light of Hellenistic philosophies, Cicero developed a legal and political thought quite suitable to Rome. I will examine some tenets showing the very Roman purpose, no less than the Greek roots, of Cicero’s “philosophy of lawµ: natural law as right reason; law as the keystone of political community; public interest as the raison d’être of law. This way of arguing about the law, emphasizing its institutional dimensions, proves to be, in the crisis years of the Roman Republic, a flawless example of legal philosophy as a reflection deeply situated in its own historical and social context