It always bugs me that the AI will grab resources my home system or relics in the influence of mining star bases. This typically happens in early game, before declaring war or United Planets referendums are practical.
I propose a minerals rights rule. Preventing mining of resources in other races influence, with the exception of war or treaty. Conceptually, trade had intergalactic rules governing it. So it wouldn't be that much of a stretch.
This could be a much bigger undertaking then I'm making it out to be. AI and game machanics can be more complex under the hood then I, the end user, realize.