The statements of the majority doctrine are based on the assumption that the Principate of Augustus was based on the auctoritas of the princeps and that only with Vespasian would this new constitutional form be institutionalized. The analysis of the sources shows, instead, how the investiture of the individual princes required the emanation of a single lex and how this was repeated for every emperor considered legitimate by the senate and the people. In conclusion, the presence of the lex de imperio from the Royal period to the Justinian era, regardless of its force and legislative effectiveness, constitutes a constant in Roman constitutional history.