The Detapa Council was the civilian governing body of the Cardassian Union. The Council was formed in the 19th century (Earth calendar), and was, technically, in control of the Central Command and the Obsidian Order. In reality, the Council had virtually no powers to control the military arm. They were, however, able to convince the military to withdraw from Bajor, despite Central Command's objections. The Council is presided over by a Chairman. (DS9: "Cardassians", "Defiant", "Return to Grace")
Following the fall of the Obsidian Order, shortly before stardate 49011, the Council, along with the Cardassian dissident movement, overthrew the Central Command, and established control over the government. Gul Dukat served as chief military advisor to the Council following the revolution. The Klingon Empire believed the coup to have been engineered by the Dominion, and used it as a reason to invade the Union in the Klingon-Cardassian War.
During the initial invasion, the Council was evacuated from Cardassia Prime aboard the Cardassian warship Prakesh, and given temporary shelter aboard the Federation space station Deep Space 9. (DS9: "The Way of the Warrior")
Dukat talked to the Detapa Council later that year, after having captured a Klingon Bird-of-Prey. Although the council were impressed by his accomplishment and offered him his old post, they also told him they would not use the data obtained to launch an offensive against the Klingons. (DS9: "Return to Grace")