The High Council is made up near-exclusively of planetary governors, who history has shown to be extremely prone to corruption, incompetence, indolence, and arrogance. We have no systems to keep their quality up that are better than what the Imperium had, except the planetary governors on the High Council are even more powerful and untouchable than before.
The Imperial Trust allowed Avernus to produce its own equivalent of Imperial Assassins. The only ones who have authority over them are Jane and Rotbart. Despite the exclusive power they give those two individuals, there's no oversight or restrictions on their use, creation, or existence. Avernus is just trusted not to do anything bad with them.
The Fabricator-General, Ecclesiarch, and Archmagos Explorator Veneratus are all based on Avernus, the most dangerous death world in the galaxy.
The reduction in power of the Ministorum reduces their ability to abuse their power, but it also makes it harder for the most moral and righteous organisation in the Trust to curb the abuses of power of other people or organisations. The power of planetary governors has increased since the Age of the Imperium so this can be pretty bad. Furthermore, the weakness of the Ecclesiarchy is what allowed Goge Vandire to gain control over it. Preventing such a thing from happening again was one of the duties of the Adepta Sororitas, but in the Trust, that job instead goes to, wait for it, planetary governors.
One way to prevent corruption in the Ecclesiarchy or planetary governors or whatever is the Inquisition. The problem with them is a catch 22 situation. They either don't have enough power to keep the Trust pure and functional, in which case the Trust becomes impure and dysfunctional, or they have enough power to keep the Trust pure and functional, in which case there is a lot more power concentrated in the Inquisition than is safe. The Imperium chose to keep the Inquisition relatively weak, but covered for it somewhat by other organisations such as the Adeptus Arbites, the Adeptus Ministorum, the Adeptus Mechanicus, and the Adepta Sororitas. In the Trust, all those organisations (the latter of whom has no real power any more) are firmly under the thumb of planetary governors.
When the rest of the galaxy burned during the Age of Strife, it was the Mechanicum of Mars that managed to keep alive the single greatest store of knowledge and technology of the Dark Age in the galaxy. In the Imperial Trust, more and more technology is being entrusted with people who simply don't care about the mystical mumbo jumbo of the tech priests, and so have significantly less issues with abusing technology, losing it, or distributing it to the unworthy. The more advanced tech is still kept by the Mechanicus, but the Mechanicus in turn is intentionally being made the obedient lap dogs of planetary governors, such as it is on Avernus. It would take only one corrupt planetary governor for there to be a better-than-comfortable chance of Chaos gaining a bunch of our tech.
The Emperor himself said to not to dabble with Abominable Intelligence and Lin hasn't said that he's rescinded that order, yet we still kept the STC for the Men of Stone. Furthermore, whether to keep the STC for the Men of Iron was a debate rather than an automatic "throw it into the sun", and the final decision was ultimately deferred to a planetary governor.
Our ways of preventing Space Marines from turning traitor (or promptly killing them if they do) are no better than the Imperium's. Despite that, we have (or will have) a small legion's worth of Space Marines within our borders.
One of the things that could potentially break the Imperial Trust is Ridcully falling to Chaos. One of the big things that can make him fall to Chaos is him looking at Chaos Gods and rolling bad. The only thing that's needed to make him look at Chaos Gods is a planetary governor telling him to do so.
All of the above is done out of convenience or because it's effective, not because it can stand the test of time.
Right, I'm dropping off in a sec, but I'm going to do some commenting before I leave.
First, yes most planatary govenors in the Imperium were shit, but that was because the system allowed and even encouraged it for most worlds except the ones that were important.
Ours doesn't do that, governors are encouraged to be the best they can be, through a variety of means. Just look at Zaren, who in many ways should be typical of an old Trust governor.
Second I think you are over stating the lack of oversight we have, for the Last Hunters. First, its Avernus, if we go chaos we have a permanent sword of Damocles hanging over our head. Second there is oversight, the Inquisition and the Trust both have observers, hell the Trust has an entire advisory board that can lock down certain actions if they feel they have too.
And yeah we are trusted not to do anything bad with them, and its a good trust, out of all the Governors we're probably the least likely to do something with them outside their mandate and they know that.
Yes they are, thankfully both seem to be spending increasing amounts of time on the moons and are still separate to Avernus *insert the usual spiel about how no we don't actually control Scott, it looks like we do for game play purposes, in universe we at best advise. Its the same reason we were the deciding voice on things like the Blood Dragons trade.
And on two fronts that's a bit of a non issue. For a start due to the milita system if a priest really felt it needed to remove a govenor they likely still could, though that's incredibly unlikely as it would require none of the other govenor's giving a shit, the Inquisition dropping the idiot ball and the Psykers not noticing an important event like this so close to home. In short basically impossible. And if a Vandire esque figure were to form the govenors would squash them flat before you can say "WAKA."
Who again are not the Govenor's of the majority of the Imperium. Do I really have to elucidate on how the system worked? Basically, most worlds like the middle of know where Hive world 2141241 and Agri world 915u23952, who cares who's in charge so long as they're competent?
Important worlds though. Recruiting worlds need good governor's like Alafric to ensure that the soldiers produced are worth something, fortress worlds need good general Governor like Creed ect. In essence if a world was important you could be damn sure the governor was effective, other wise the imperium just didn't give a shit.
The tech priests sure as shit had few issues about distributing their technology they just hoarded the best bits and ensured that wars were lost because nobody, but them could use it. And if you're so worried about chaos getting our stuff then you'd be against tech trading with Callamus, or Ultramar or Vulkan all of whom are much more vulnerable to chaos infiltration due to sheer size if nothing else. I'd also like to ask how our prospective tech trader is going to hand over this technology? He can't project it through the warp and unless the Inquisition goes tits up a spy isn't going to have time to get in and get out with it, and forget smuggling a sorcerer in.
No the final decision was differed to the Fabricator General, as I recall Durin said he did a hidden roll to both to determine whether Britton threw them into the sun. Our roll offered a bonus to keep the MoS STC, and a malus to the MoI, but it was his decision.
As for Lin
@Durin
1. Have we asked him if the Proclamation on AI has been rescinded?
Lets hear it straight from the hoses mouth.
And yeah Ridcully falling would be bad, no shit.
No offence (meaningless I know), but this seems like a lot of panic over bugger all. All your problems apply to the Imperium, just replace planetary governor with High Lord of Terra. If even one of them was corrupted or incompetent it was disastrous for the rest of the Imperium same for the Trust. Difference for the Trust is that unlike with the high lords problems emerging will likely take a lot longer and are small enough in scale that we can fix them.