The Ni'novian Republic was a short lived governmental form that replaced the Ni'novian Empire and was replaced by the Order of Sovereignty. It started a little more than two months into 46 ABY, shortly after the end of the Galaxial War. With the War over, the Ni'novians believed it was time to remove the Emperorship that Trivas held and go with a more democratic government.
The government was divided into three branches. The Executor, the Consuls, and the Senate. Each branch had specifically defined powers and responsibilities as defined in the Constitution of 46 ABY. The government was passed by vote of the entire population of the Ni'novian Empire and the government was established.
When Trivas was killed, Vexen became the Executor for a short time until his involvement in the Yavin Crisis and other problems jeopardized his spot. He was not impeached, but rather joined with the Imperialists in the Sith Revolution. Scyrone was the second Senate Leader and tensions arose between him and Kracor over who would take the spot of Executor should Vexen be impeached. Others within the government favored the return to the Imperial style of government and sides were taken. During the non-violent Sith Revolution, the Ni'novian Republic was abolished and replaced with the Order of Sovereignty.