[3] The son of Lucius and a member of the Roman tribe Camilia, Carus' career began with his appointment to the decemviri stlitibus judicandis, one of the four boards of the vigintiviri; membership in one of these four boards was a preliminary and required first step toward gaining entry into the Roman Senate.
[4][5] Returning to Rome, Carus began his climb up the series of Republican magistracies: he was first appointed quaestor to the Emperor, then Plebeian Tribune before achieving the Praetorship.
[4] Returning to the military sphere, Carus was granted the rank of Legatus legionis, commanding the Legio XXX Ulpia Victrix.
Anthony Birley notes that this was an unusual assignment, for Legio XXX and Legio IX were both stationed in the same province, Germania Inferior, and men were rarely assigned command of a legion in the same army as they had held a tribunate; Birley could only list 14 men with that distinction.
His next assignment was as Legatus Augusti pro praetore (or governor) of the Roman province of Arabia Petraea from AD 142 to 143.