How the Roman Republic Became the Roman Empire

Lex de Imperio

The Lex de Imperio Vespasiani was a pivotal document that outlined the powers of the Roman emperor, marking a significant shift in governance. Gary Arndt explains that this document, created after Emperor Vespasian's rise in 69 AD, detailed the emperor's authority to endorse office candidates, expand city boundaries, and act in the state's interest. Despite these powers being theoretically granted by the Senate, they signified the gradual centralization of power.

The powers clearly had expanded by this time, but they were still, at least in theory, given by the senate to keep up the illusion of the republic.

--- Gary Arndt

This centralization was a precursor to the eventual transformation of the Roman Republic into an empire, with emperors adopting the title of Caesar as a symbol of their authority 1.

   

Dominate System

The transition from the Principate to the Dominate marked a fundamental change in the Roman Empire's structure. Gary Arndt highlights how Emperor Domitian's reforms in 284 AD shifted the empire closer to a monarchy, dividing it into halves ruled by a senior Augustus and a junior Caesar. This system formalized the emperor's autocratic power, though the Senate continued to officially approve new emperors.

The dominate differed from the principate in that the empire became much closer to a monarchy.

--- Gary Arndt

The Dominate system underscored the emperor's role as an autocrat, with the Senate's approval serving as a mere formality, reflecting the slow but steady accumulation of power initiated by Augustus 1.