In AD 212, all free inhabitants of the Empire were granted citizenship by the Constitutio Antoniniana, with the exception of the dediticii, people who had become subject to Rome through surrender in war, and freed slaves.
For example, one estimate puts Roman citizens in Britain c. AD 100 at about 50,000, less than 3% of the total provincial population of c. 1.7 million.
Peregrini were subject to de plano (summary) justice, including execution, at the discretion of the legatus Augusti (provincial governor).
This would involve the governor acting as judge, advised by a consilium ("council") of senior officials, as well as the right of the defendant to employ legal counsel.
[14] In the social sphere, peregrini did not possess the right of connubium ("inter-marriage"): i.e. they could not legally marry a Roman citizen: thus any children from a mixed union were illegitimate and could not inherit citizenship (or property).
[16] Civitates peregrinae were based on the territories of pre-Roman city-states (in the Mediterranean) or indigenous tribes (in the northwestern European and Danubian provinces), minus lands confiscated by the Romans after the conquest of the province to provide land for legionary veterans or to become imperial estates.
[17] Provided that the civitates collected and delivered their assessed annual tributum (poll and land taxes) and carried out required services such as maintaining trunk Roman roads that crossed their territory, they were largely left to run their own affairs by the central provincial administration.
The civitates peregrinae were often ruled by the descendants of the aristocracies that dominated them when they were independent entities in the pre-conquest era, although many of these may have suffered severe diminution of their lands during the invasion period.
They ensured the loyalty of those elites by substantial favours: grants of land, citizenship and even enrollment in the highest class in Roman society, the senatorial order, for those who met the property threshold.
[20] These privileges would further entrench the wealth and power of native aristocracies, at the expense of the mass of their fellow peregrini.
The Roman Empire was a society with enormous disparities in wealth, with the senatorial order owning a significant proportion of all land in the empire in the form of vast latifundia ("large estates"), often in several provinces e.g. Pliny the Younger's statement in one of his letters that at the time of Nero (r.54–68), half of all land in Africa proconsularis (Tunisia) was owned by just 6 private landlords.
[22] Indeed, the senatorial order, which was hereditary, was itself partly defined by wealth, as any outsider wishing to join it had to meet a very high property qualification (250,000 denarii).
Much land may have been confiscated from members of those native elites who opposed the Roman invaders, and, conversely, granted to those who supported them.
In particular, many free peasants who had farmed the same plots for generations (i.e. were owners under tribal customary law) would have found themselves reduced to tenants, obliged to pay rent to absentee Roman landlords or to the agents of the procurator, the chief financial officer of the province, if their land was now part of an imperial estate.
[27] Peregrini could also acquire citizenship individually, either through service in the auxilia for the minimum 25-year term, or by special grant of the emperor for merit or status.
[28] In addition, bribery of governors, or other high officials, was undoubtedly a much-used route for wealthy peregrini to gain citizenship.