I don't think this answer fits to the game. A black market is a place where you can buy things cheaper.
This post by Steve is scrap.
Admins, please delete such irrelevant message.
Its a research dependant upgrade. If you have "care packages" then it reduces the cost of using the "carepackage" ability (which removes battle fatigue in a region for a turn and at higher levels lasts the 2 turns instead of just one)