High Quality Content by WIKIPEDIA articles! The executive magistrates of the Roman Empire were elected individuals of the ancient Roman Empire. During the transition from monarchy to republic, the constitutional balance of power shifted from the executive (the Roman King) to the Roman Senate. During the transition from republic to empire, the constitutional balance of power shifted back to the executive (the Roman Emperor). Theoretically, the senate elected each new emperor, although in practice, it was the army which made the choice. The powers of an emperor, (his imperium) existed, in theory at least, by virtue of his legal standing. The two most significant components to an emperor`s imperium were the "tribunician powers" (potestas tribunicia) and the "proconsular powers" (imperium proconsulare). In theory at least, the tribunician powers (which were similar to those of the Plebeian Tribunes under the old republic) gave the emperor authority over Rome`s civil government, while the proconsular powers (similar to those of military governors, or Proconsuls, under the old republic) gave him authority over the Roman army. While these distinctions were clearly defined during the early empire, eventually they were lost, and the emperor`s powers became less constitutional and more monarchical.