by Kevin Blood
To understand the political, social, economic and military developments that happened in Rome in the middle and late republican periods, it is important to understand the manner in which early republican society functioned and was organized. The relative positions of Roman citizens in the political, religious, legislative, social, economic and military bodies of the early Roman state was ordered by the sharp distinctions between the Patrician and Plebeian classes.
Gens – clans
The primary unit of early Roman society was the family household (familia). Numbers of related households of families (familiae) constituted a clan. These clan units, gentes (clans), made up of families who were descended from a common ancestor, these clans also had certain religious rites in common.
The basic political organisation of the republic.
With the deposition of the last of Rome’s kings c.509, Rome replaced the monarchy with a form of republican government. The government was structured like so: the consuls – two patrician magistrates, the senate – council of the nobility, and the comitia curiata – the people’s assembly.
The assembly of the people
What was known as the comitia curiata, the curiate assembly, came from the regal period of Roman history. Divided into four ‘parishes’ (curiae) with the people of each voting according to their curia, they elected the consuls, and they voted for or against any proposals the consuls proposed to the curiae. The power to instigate reforms sought by the assembly was limited by the fact that it could not raise or discuss any issues related to proposal of a consul.
The Senate
To begin with, the senate was limited to 100 members, this eventually increased to 300. These were drawn solely from the patrician clans. If found guilty of serious misconduct, a senator could be expelled from the senate, otherwise a senatorial seat was for life. The senate’s main function was to be an advisory body to consuls. Should the senate not approve of a resolution made by the assembly it reserved the power of veto, so that the assembly might pay attention to the advice of the senate.
The senate’s primary role was to advise the consuls and the assembly, yet, from the third century its power and influence had considerably grown, it became, in effect, the prime-mover in republican politics in the second and first centuries.
Roman Senate
Roman Senate
The consuls
Powers: Imperium, auspicium, the right of veto.
The symbol of consular power and executive authority were the fasces, these represented the consul’s imperium. The fasces, a double-headed axe bound in a bundle of rods (and the origin of the word ‘fascism’), was used by the attendants of the consul, the lictor. This potent symbol of unity under a central authority and threat of violence showed the populace the consuls’ power to administer justice and punishment; through his power to flog. Consular imperium gave them total executive authority over the military, civil and judicial matters, and the power to command an army. They could be recognised by their toga praetexta, with purple border, which suggested powers similar to the kings of old, a colour associated with royal authority and deity.
Important to consular imperium was the right of auspicium, the right to take the auspices so as to interpret divine will and approval for prominent public acts.
To avoid tyranny, the were two consuls with equal powers, each had the power of veto (to halt or prevent the actions of their opposite).
The limitations
Collegiality and annuality were important checks on consular power.  The collegiate nature of the position of consul (shared powers) permitted that consuls could act as check on each other.  The occupation of consul being prescribed to a one-year term was a real attempt at the limitation to consular power hording. These checks and balances were meant to reflect a desire to move distinctly away from the autocratic power of monarchy.
Consular power in the early republican era was potent and apparent, however Rome’s expansion meant that over time the ability of two individuals to administer the apparatus of state power became increasingly untenable.  This meant that many the original functions of the consuls were devolved to a greater number of magistrates.  The close of the fourth century saw the Roman magistracy inherit the form it would maintain until the end of the republic.
Source
Bradley, P. (2003) Ancient Rome; Using Evidence, Cambridge, Cambridge University Press, pp.35-43.