It seems, however, that about the time of Julius Caesar’s dictatorship the belief in the incompatibility of two citizenships was abandoned. We find that in the triumviral period his adopted son, later Augustus, grants to a Syrian sea-captain citizen-privileges that are clearly meant to be used in his own home, even though he is to be registered in a Roman tribe: citizenship is extended to his parents, wife, sons, and grandsons without qualification; they are to be free from Roman taxation and other burdens, while the Syrian captain is to possess a similar recourse to Roman magistrates, when bringing or defending a lawsuit, as the captains in 78 bc (FIRA I.55 = trans. Sherk 1984 no. 86). The converse of this development can be seen in Augustus’s third Cyrene edict of 7-6 bc, where he orders those honored with Roman citizenship to perform their local civic obligations as Greeks, unless they have been specifically granted immunity from them with their Roman citizenship (FIRA I.68 = Sherk 1984 no. 102, III). The emphasis is now on not separating those rewarded with Roman citizenship from their local communities.
Julius Caesar had extended Roman citizenship over the rest of Cisalpine Gaul from the Po to the Alps. He also planned to give Latin rights to Sicily, a project abandoned after his death. However, there were no mass extensions of citizenship beyond what is now Italy either then or in the first two centuries of the principate. What we find is a few grants to cities - Gades, Utica, Tingi, and Volubilis - and a considerable, though ultimately unquantifiable, number of grants to individuals. Of course, the settlement of Roman citizens in colonies overseas spread the citizenship geographically. Furthermore, the creation of municipia with Latin rights provided an automatic route for local elites to achieve citizenship through the tenure of a local magistracy (this was extended to the whole local senate by Hadrian). Vespasian granted Latin rights to the cities of Spain, and the survival on bronze of most of the local constitution given to the small town of Irni under Domitian now provides us with an illustration of how this worked (Gonzalez 1986, Fear, the iberian peninsula, section 4). The ex-magistrates in these towns were not exempted from local duties and burdens through their citizenship, nor were either the acquisition of citizenship nor the general subjection of Latin communities to Roman law allowed to infringe the rights possessed earlier under local law.
Roman citizenship remained a privilege in the early empire. Its value as a means of political activity under the principate was at a discount even to the population of Rome, as the Roman assemblies became more ceremonial than the source of effective decisions. It did, however, give the wealthier potential access to political careers and membership of the senate, and in time the latter came to contain a good representation of provincials. At a lower level it allowed men to be recruited into the Roman legions - better paid and affording greater prospects of military and civil promotion than the non-Roman auxiliaries. It also retained one important feature of the citizenship of the republic - provocatio, the right of appeal that entailed protection against arbitrary action by Roman magistrates and their subordinates, including official brutality. This was now associated with the invocation of the name of the emperor, as illustrated in the story of St Paul.
The privilege remained a privilege by virtue of being limited. This was also enforced in the realm of manumission under Augustus by legislation that put precise limits on the number of manumissions that might be made and on the age of manu-mitters and manumitted. It also stigmatized informal manumission by relegating those so liberated to the degraded category of Junian Latins, which they could only escape through a marriage to someone of equal or superior status and the production of a 1-year-old child. Nevertheless, in Rome and the cities of Italy the evidence of funerary inscriptions makes it clear that the vast majority of the poor could trace their descent back to a slave.
The situation in the Roman empire was changed radically in ad 212: “The emperor Caesar Marcus Aurelius Severus Antoninus Augustus [Caracalla] declares: . . .I may show my gratitude to the immortal gods for preserving me. . .if I can incorporate whoever joins my people into the worship of the gods. Accordingly, I grant Roman citizenship to all aliens throughout the world, with every form of citizen body remaining, except the dediticii [those in the condition of surrendered enemies with no rights] . . .” (FIRA I.88). The contemporary historian Cassius Dio (77.9.5) saw this as an emergency measure to make up for a deficit in imperial revenue. However, it had the long-term consequence of extending the principle of double citizenship - of Rome and of one’s own community - to all free people in the empire. The resulting citizen body would have seemed totally anomalous to Aristotle, but has more in common with those of certain super-states of today, the United States of America and the European Union.