There was some mention of an organised band of Vargr smugglers in the Gateway sourcebook. I'd love to know more about that.
On the point of slavery there seems to be almost no mention of it in canon. However, it's implied that the Empire doesn't approve of slaves (else it would be institutional). IMTU the sanction against slavery is Imperial High Law; however, this applies just to the interplanetary trading of slaves. If an Imperial planet has institutionalised slavery when it joins, the local autonomy laws must allow that to continue. It won't be able to either import or export slaves, so the market is internal and 'traditional'. The Imperium would probably then work clandestinely with influence to end the trade.
when thinking of the Sol Rim, slavery does become more common. I'm guessing this is due to associations with the word 'confederacy'. It's probably an economic thing, with the slaves being called "indentured servants". There's probably a futures market in it.
Slavery would be a heinous crime, but with a good economic return (rounding up colonists and shipping them to a hellhole mine for instance). You can see looking at our world that slavery of a sort can exist even in our western societies. Hence the people trafficker, snakeheads, and the fact that 30 Chinese people can be allowed to drown on an estuary not too far from where I live.
Of more concern is the viability of piracy. If pirates need safe havens to sell their ill gotten gains then life's gonna be hard for them in Traveller. If Granicus is such a necessary pirate haven then worlds to coreward/trailing would have little to fear as J4 ships are hard to come by. So IMTU the pirates are backed up by a shadow organisation that handles deep space refuelling, and transfers stolen cargoes to 'friendly' legit traders so it can be sold on an open market. This org is more powerful than any pirate gang, but whether it is a single syndicate or consortium is unknown.
Another possible avenue for interstellar organised crime is in data trafficking. Stock exchange info is highly prized and useful to any investor, so getting the figures ahead of everyone (ie: ahead of the X-boat) would be mighty valuable indeed. So a cartel runs clandestine J-5 or even 6 vessels that take the publicly availiable stock info and jump ahead of the X-boat network, crossing rifts etc. This is marginally illegal, but highly profitable, and the cartel will use extreme measures in keeping their hold on it. It's essentially getting the race results ahead of the bookies, a traditional mafia passtime.
As to other forms of organised crime, the nature of Traveller means they'll be few and far between. More like secret societies than crime orgs, tied by common traditions and rituals rather than economically bound. They'd be more like warlords. Individual 'dons' wouldn't generally have influence over one planet, let alone other systems. Ones that did would be fairly legitimate in the main and be called 'corporations'. Business is after all a form of legalised theft!
thats my input, for what its worth.
