The greatest strength of the Roman system of government was also its greatest weakness: the reliance on precedent. The way the government was formally constituted was not the way it operated in practice. The Senate, for example, was technically an advisory body without formal role. Laws could be passed through...
The greatest strength of the Roman system of government was also its greatest weakness: the reliance on precedent. The way the government was formally constituted was not the way it operated in practice. The Senate, for example, was technically an advisory body without formal role. Laws could be passed through the people's assemblies without need for the Senate. Tribunes also had veto power over the laws put forward in the Senate. Consuls could serve more than one term in a row because no law said they couldn't.
Of course that's not how it worked in practice. It was unthinkable to Romans of a middle Republic that laws would be passed without the Senate. The Romans regarded their republic as sacrosanct and thus wouldn't violate its precedents for fear of incurring the wrath of the Gods.
In the late Republic, however, the stakes rose ever higher in the contest between the Optimates and the Populares. The influx of wealth and slaves from conquest disproportionately benefited the wealthy while the common people lost their farms and tradesmen lost work to slaves. As the need for reform became ever more pressing, the Optimates dug in their heels, using the Senate as a roadblock to any reform legislation. Their stubborn adherence to this tactic and refusal to compromise is what finally provided the incentive for reformers to break precedent.
The Gracchi brothers began the unraveling by using the tribune's veto to block all legislation, standing for office for successive terms, and proposing legislation. None of these acts was illegal per se, they were just violations of generally accepted rules. In response, the Optimates introduced their own unfortunate precedent: retaliatory violence. Once the conflict broke into the open in such ways, the system became more perverted. Roman soldiers no longer needed property to join the legions, becoming more loyal to their commanders than the state. Marius, with the backing of loyal soldiers, became consul seven times. He and Sulla marched on Rome with armies, purging each other's followers.
A victorious Sulla tried to bring back the conservative regime by creating the cursus honorum, but no amount of law could undo the example he and Sulla had set by attaining power through violence. The First Triumvirate finally managed to circumvent the Senate without retaliation by pooling their wealth, political, and military strength. The Republic was practically dead at that point. When the Senate declared Caesar an enemy of Rome and he crossed the Rubicon in 49 BC, his action was no longer shocking because the precedent of violence had been so firmly established.