Slavery

Although it is outlawed within the Dominion and has never — been practiced among the Exiles, slavery is still present on the Galactic Fringe - and even the planet Nexus - thanks to the presence of Fringe criminal organizations such as the Darkspur Cartel. These slaves are generally prisoners, taken to either perform hard labor for their captors or to be sold offworld to planets where slavery still thrives.

Source:
The game journal.