The criminal underworld of the Milky Way is divided into two parts and has been since the war came to an end and the AEC was shattered. The two halves that comprise the criminal landscape are referred to as the Upper Underworld and the Lower Underworld. Each criminal sphere, much like a government, has a capital, and is 'governed' by one, absolute authority. They are in direct competition with one another on levels that most average criminals don't understand. They are explained in greater detail below.
Home to all of the 'high' crime in the galaxy. This is the realm of grifting (social engineering), theft, hacking, counterfeiting, and high-end assassinations and weapons trafficking. The Upper Underworld is full of criminals that could be seen as artists, who take a great deal of pride in their work. Honour amongst thieves is a common theme in this half of the criminal landscape. The capital of this sphere is Grand Central Station, a huge space station. The leader of this sect is the mysterious Queen of Crows, a human crime lord of immense power.
Home to the 'low' crime in the galaxy. This is the realm of crude gangs, drugs, off-market cybernetics, prostitution, rape, and cheap weapons. The Lower Underworld is full of criminals that are just thugs, nothing more. They're money hungry vultures that will do absolutely anything and kill absolutely anyone. There is no honour here. The capital of this sphere is Tuurnengard, an artificial planet. No one knows who controls this amalgam of vicious and dark criminals.