I'd say your very examples are proof that oversight does work, in general. And you are imposing your personal views on those doing the overseeing, namely the b

I'd say your very examples are proof that oversight does work, in general. And you are imposing your personal views on those doing the overseeing, namely the branches of government. From their point of view, such "overreaches" may not necessarily be that far. Also, the respective presidents didn't only know about the programs, they ordered them. And the oversight committees mostly new about that, also. I'm not saying that nothing went wrong, but the level of oversight in the US system of government does provide better "worst case" guarantees than in many other nations. And in the end, pretty much every significant wrong-doing seems to come to light, often through the political process or in case that is too slow, the media.