This chapter considers the concept of the emperor who obeys the law, which persists throughout the Principate but which emerged in the late first century CE. I first discuss the lex de imperio Vespasiani, which portrayed imperial power as the object of a senatorial grant and thus constructs Vespasian as a kind of legally empowered agent rather than an omnipotent sovereign. I then discuss an edict of the emperor Titus which reaffirmed prior imperial grants en masse, and argue that this not only made it possible for emperors to exercise more granular control over the Roman world, but also analogized Titus’ position as Vespasian’s successor to that of a son succeeding his father under the Roman law of obligations. Finally I consider how Pliny describes Trajan’s engagement with law in the Panegyricus, and how Trajan uses law as a medium for the performance of legal and political subjecthood.

The first four principes after Augustus all ruled by virtue of their relationship to the founder of the principate. By the end of the reign of Nero, few men were left who could claim to be descended from Divus Augustus. This led to a series of civil wars, won by a man who had no familial relationship with the domus Augusta. By AD 69, the position of princeps had been codified beyond the hereditary charisma of Augustus. But as we see in the lex de imperio Vespasiani, the Senate recognized the legal claim of Vespasian to rule as princeps was based on the original position created by Augustus, a position solidified by the attitude and actions of Augustus’ successor, Tiberius.