In the Roman Republic, the dictator, was an 'extraordinary magistrate' (magistratus extraordinarius) with the absolute authority to perform tasks beyond the authority of the ordinary magistrate (magistratus ordinarius). The office of dictator was a legal innovation originally named Magister Populi (Master of the People), i.e., Master of the Citizen Army. The term was derived from dicto to dictate or prescribe.The Roman Senate passed a senatus consultum authorizing the consuls to nominate a dictator — the sole exception to the Roman legal principles of collegiality (multiple tenants in the same office) and responsibility (legal liability for official actions) — only one man was appointed, and, as the highest magistrate, he was not legally liable for official actions; 24 lictors attended him. Only a single dictator was allowed, because of the imperium magnum, the great, extraordinary power with which he could over-rule, or depose from office, or put to death other curule magistrates, who also possessed imperium.There were several forms of dictator, distinguished by their causa, or reason for their creation. The most common form, and the one most associated with the Roman dictator, was rei gerundae causa, ""for the matter to be done"", which almost always involved leading an army in the field and specified the enemy to be combated. At least one dictator (and possibly more) was designated seditionis sedandae et rei gerundae causa, ""for the putting down of rebellion and the matter to be done."" Dictators were also appointed to serve administrative or religious functions, such as holding elections (comitiorum habendorum causa, the second most common form of dictatorship) or driving a nail into the Temple of Jupiter Optimus Maximus to end a pestilence (clavi figendi causa).Rome ceased to appoint dictators after the time of the Second Punic War. The office was revived during the Roman Civil War by Lucius Cornelius Sulla Felix, who was appointed dictator legibus faciendis et rei publicae constituendae causa (dictator for the making of laws and for the settling of the constitution). Julius Caesar was also named dictator on several occasions. The Roman emperors eschewed use of the title to avoid the opprobrium it attracted as the result of these last two dictators.