A consul was the highest elected public official of the Roman Republic ( to 27 BC). Romans considered the consulship the second-highest level of the cursus honoruman ascending sequence of public offices to which politicians aspiredafter that of the censor, which was reserved for former consuls. Each year, the Centuriate Assembly elected two consuls to serve jointly for a one-year term. The consuls alternated each month holding fasces (taking turns leading) when both were in Rome. A consul's imperium (military power) extended over Rome and all its provinces.
There were two consuls in order to create a check on the power of any individual citizen in accordance with the republican belief that the powers of the former kings of Rome should be spread out into multiple offices. To that end, each consul could veto the actions of the other consul.
After the establishment of the Empire (27 BC), the consuls became mere symbolic representatives of Rome's republican heritage and held very little power and authority, with the Emperor acting as the supreme authority.
History
Under the Republic
According to Roman tradition, after the expulsion of the last king, Tarquin Superbus, the powers and authority of the king were given to the newly instituted consulship. Originally, consuls were called praetors ("leader"), referring to their duties as the chief military commanders. By at least 300 BC the title of consul became commonly used. Ancient writers usually derive the title consul from the Latin verb consulere, "to take counsel", but this is most likely a later gloss of the term, which probably derives—in view of the joint nature of the office—from con- and sal-, "get together" or from con- and sell-/sedl-, "sit down together with" or "next to". In Greek, the title was originally rendered as , strategos hypatos ("the supreme general"), and later simply as ὕπατος (hypatos).
The consulship was believed by the Romans to date back to the traditional establishment of the Republic in 509 BC, but the succession of consuls was not continuous in the 5th century BC, when the consulship was supposedly replaced with a board of consular tribunes, which was elected whenever the military needs of the state were significant enough to warrant the election of more than the usual two consuls. These remained in place until the office was abolished in 367 BC and the consulship was reintroduced.
Consuls had extensive powers in peacetime (administrative, legislative, and judicial), and in wartime often held the highest military command. Additional religious duties included certain rites which, as a sign of their formal importance, could only be carried out by the highest state officials. Consuls also read auguries, an essential religious ritual, before leading armies into the field.
Two consuls were elected each year, serving together, each with veto power over the other's actions, a normal principle for magistracies. They were elected by the comitia centuriata, which also elected praetors and censors. However, they formally assumed powers only after the ratification of their election in the older comitia curiata, which granted the consuls their imperium by enacting a law, the lex curiata de imperio.
If a consul died during his term (not uncommon when consuls were in the forefront of battle) or was removed from office, another would be elected by the comitia centuriata to serve the remainder of the term as consul suffectus ("suffect consul"). A consul elected to start the yearcalled a consul ordinarius ("ordinary consul")held more prestige than a suffect consul, partly because the year would be named for ordinary consuls (see consular dating).