The Cardassian Union (also referred to as the Cardassian Empire or Cardassia) is the official governing body of the Cardassian people. The capital world is Cardassia Prime.
Cardassian history is perhaps one of the most brutal histories of any species inhabiting the Alpha Quadrant. Originally, the Cardassian homeworld was that of a deeply spiritual and artistic people, which soon fell into decay when famine and plague struck their civilization. Over the years, Cardassian society evolved to adopt a philosophy that sacrificed their individual freedoms for the greater good of the state and their society. For over five centuries, the iron fisted Cardassian military sought to solve Cardassia's problems through the conquest of numerous worlds and species throughout the galaxy, leading to an era of expansion and conflict. This ultimately left Cardassian civilization in ruins once again after suffering the staggering losses of two major wars.
The Cardassian Union was formed under a treaty that established a power-sharing agreement between the Cardassian Central Command and the Obsidian Order. Friction always existed between the two organizations as the Central Command worked to expand the reaches of the Union and the Obsidian Order worked to suppress it. The civilian Detapa Council was established to serve as the chief governing body between the two branches, however, in practice, the Council was virtually powerless.
In late-2371 or early-2372, following the fall of the Obsidian Order at the Battle of the Omarion Nebula, the Detapa Council and the Cardassian dissident movement overthrew the Central Command, establishing control over the government.
In 2373, Gul Dukat secretly negotiated with the Dominion for the Cardassian Union to become its newest members. The Detapa Council was overthrown and Gul Dukat established himself as ruler of the Cardassian Union. This arrangement was later revealed to be inaccurate as Dukat (and his successors Legate Damar and Legate Broca) were actually subservient to the Vorta and the Founders.
The Cardassian military was lead by the Central Command and the Cardassian forces were divided into several orders. The Obsidian Order, the intelligence agency of the Union, was sometimes referred to as part of the structure of the Cardassian military orders.
The highest court of justice in the Cardassian Union is the Cardassian Supreme Tribunal. The Cardassian Articles of Jurisprudence provide the laws governing treatment and rights of prisoners in the Cardassian justice system
See the original version at Memory Alpha