Describe and explain the evolution of the Roman Republican Constitution from its origin to 31 BC (battle of Actium)

One of the most important features of Roman Republic was the justice system and the laws. Most countries all over the world have Constitutions which are based on the same logic with the Roman Constitution. A further analysis on the origins of Republican Constitution should be based on the origins of Roman Republic. After expelling the least Etruscan king, Tarquin the Proud, Romans established a republic. They mainly adapted the Etruscan governmental system and the laws, and developed some specific institutions also. Only patricians were eligible to have governmental positions in the begging. Main characteristics of republican institutions were that, at every level, two or more equals elected for fixed terms shared power. The king's position was given to the consuls who were elected for one-year terms. Senate was responsible for taking the last decision, however the most important members of the senate were consuls and aftertimes what they said was accepted. The magistrates rose through a series of increasingly important offices. This structure is called "cursus honorum". This bureaucratic hierarchy included: quaestors responsible for the Treasury, Aedile curules who looked after the city, praetors were in charge of administration of justice and commanded armies in war, consuls were presidents of the senate and censors who revised the senate list.

A complex system of laws began roughly with the publication of the Law of Twelve Tables. The main cause of the declaration of the law of Twelve Tables is the struggle between "patricians" (the elites) and the plebeians or the public people. The plebs began to organize in response to patrician control. In time plebeians created their own assembly "the consul of plebs" which enacted laws binding on all plebeians. This consul consisted of magistrates called "tribunes". The military pressure of the surrounding cities and tribes forced patricians to compromise with the plebeians. In the end they accepted the law of Twelve Tables which consisted of laws which applied on all free citizens. Law of Twelve Tables mainly consisted of private, criminal, sacred and public matters. A few examples are the rules and preliminaries for the trial of a criminal, law of table, law of execution, rights of head of the family, positions of humans, public laws and marital laws such as the prohibition of mirage between patricians and plebeians. Gradually priesthood, magistracies and senate opened to plebeians. A major achievement of plebeians is the validity of the decisions of the plebeian assembly over all citizens, patricians and plebeians alike.

In the later centuries Law of Twelve Tables was transformed with the growth of the country. Main sources of these new additions emanated from the change in custom, from the teaching of Stoics, form the decision of judges and especially from the decrees of governors. Perhaps the most important of these governors was Gaius Julius Caesar. He made radical reforms in law. He enlarged the formerly 400-people- senate to 900 and widened its presentation, appointing soldiers, freedom, provincials and wealthy men from other Italian cities. He doubled the numbers of all magistrates (praetors, censors, quaestors etc.) to increase the efficiency of the government. He gave the right to be a Roman citizen to the other towns natives to gain both political advanteges and proponents when fighting with other tribes and cities. And he changed the dictatorship form six months to lifetime for himself which essentially caused his assassination.

The most interesting and in many ways the most important resource of the Roman Law was the natural law, a product of philosophy, especially the Greek Philisophy. The Stoics developed the ideas of rotational order of nature, which is the manifestation of justice of right. They had claimed that all men are in nature equal and they are entitled by a series of rights which no government have any authority to cancel them. The most important figure who defended and systematized the stochastic though was Marcus Tullius Cicero, a well-educated senate member. He declared that "The law is right reason consonant with nature, diffused among all men, constant, eternal. To make enactment infringing this law, religion forbids, neither may it be repeated in part, nor have we power through senate justice as a legal principle was one of the most significant achievements of the Roman civilization.

In general, the scheme of the Roman Republican Constitution and laws were told above. Consequently, there is a general agreement that one of the most important concept which the Romans inherited to the succeeding cultures was their system of law.