The end of the Roman Republic was signaled by the transformation of political disputes into criminal prosecutions.
The Romans had always dabbled with a dangerous brew of political trials and private prosecutors. There were no public prosecutors, so even criminal charges had to be brought by a citizen. From time to time, Senators and prominent Roman figures would launch an attack via a criminal charge – but though the motives might have been political, the substance of the charges usually rested on a ciminal act which violated the Roman legal standards.
Ominous things began happening in the 2nd century BC. The great wealth acquired by the Republic during its expansion around the Mediterranean aroused great passions, rivalries, and jealousy. Triumphant generals became wealthy men. Wealthy men became generals commanding great armies. The armies of the Senate and People of Rome became the army of Marius or the army of Sulla. And, in the next generation, the army of Pompey or the army of Julius Caesar.
At the same time, political rivals sought not just to achieve political victory over their rivals, they began to seek their rivals destruction. When they began to seek the criminal conviction of their political rivals over policy differences the end of the Republic was at hand.
Case in point. Julius Caesar had immunity from criminal prosecution so long as he was the commander of the army of the Roman Republic in Gaul. But once he surrendered that command, he could be charged and tried as a criminal in the Roman courts. This is what his political rivals threatened to do.
Facing the threat of criminal prosecution, there was little to deter Caesar from leading his army south from Gaul and using it to seize power in Rome. His rivals demanded that he surrender his command. He knew that if he did, he would likely be destroyed. He justified his march on Rome as an act of self-defense.
If the leaders of one political party threaten to prosecute the leaders of a rival political party as criminals, once they acquire control of the government, they create a powerful incentive for the other party to fight, by fair means or foul, to retain power.
This is not a happy development in our political life.