Each emperor was constitutionally invested with his powers by the formality of a decree passed in the Senate, followed by a comprehensive law enacted in the popular assembly. This bronze tablet - the sole extant document of its kind - contains the end of the law of investiture which conferred the imperial powers upon Vespasian, enumerating the various rights that had in one way or another accrued to the emperor during the first century of the Principate. The formulas of this enactment, however, are mainly those of a decree of the Senate rather than of a law. The explanation lies in the fact that the Senate first decreed the imperium to Vespasian, about December 20, A.D. 69, and the assembly subsequently incorporated this decree of the Senate in its own statute, enacted early in January, A.D. 70. Vespasian, however, dated the beginning of his reign from July I, A.D. 69, when he was acclaimed emperor by the legions in Egypt.
...that he shall have the right, just as the deified Augustus and Tiberius Julius Caesar Augustus and Tiberius Claudius Caesar Augustus Germanicus had, to conclude treaties with whomever he wishes;
And that he shall have the right, just as the deified Augustus and Tiberius Julius Caesar Augustus and Tiberius Claudius Caesar Augustus Germanicus had, to convene the senate, to put and refer proposals to it, and to cause decrees of the senate to be enacted by proposal and division of the house;
And that when the senate is convened [in special session] pursuant to his wish, authorization, order, or command, or in his presence, all matters transacted shall be considered and observed as fully binding as if the meeting of the senate had been regularly convoked and held;
And that at all elections especial consideration shall be given to those candidates for a magistracy, authority, imperium, or any post whom he has recommended to the Roman senate and people or to whom he has given and promised his vote;
And that he shall have the right, just as Tiberius Claudius Caesar Augustus Germanicus had, to extend and advance the boundaries of the pomerium whenever he deems it to be in the interest of the state;
And that he shall have the right and power, just as the deified Augustus and Tiberius Julius Caesar Augustus and Tiberius Claudius Caesar Augustus Germanicus had, to transact and do whatever things divine, human, public, and private he deems to serve the advantage and the overriding interest of the state;
And that the Emperor Caesar Vespasian shall not be bound by those laws and plebiscites which were declared not binding upon the deified Augustus or Tiberius Julius Caesar Augustus or Tiberius Claudius Caesar Augustus Germanicus, and the Emperor Caesar Vespasian Augustus shall have the right to do whatsoever it was proper for the deified Augustus or Tiberius Julius Caesar Augustus or Tiberius Claudius Caesar Augustus Germanicus to do by virtue of any law or enactment;
And that whatever was done, excuted, decreed, or ordered before the enactment of this law by the Emperor Caesar Vespasian Augustus, or by anyone at his order or command, shall be as fully binding and valid as if they had been done by order of the people or plebs.
If anyone in consequence of this law has or shall have acted contrary to laws, enactments, plebiscites, or decrees of the senate, or if he shall have failed to do in consequence of this law anything that it is incumbent on him to do in accordance with a law, enactment, plebiscite, or decree of the senate, it shall be with impunity, nor shall he on that account have to pay any penalty to the people, nor shall anyone have the right to institute suit or judicial inquiry concerning such matter, nor shall any [authority] permit proceedings before him on such matter.
From Roman Civilization. Volume II: The Empire, ed. N. Lewis and M. Reinhold, 3rd ed. (New York, 1990), pp. 11-13.