> This continuity can be explained by the “double government” theory

It could also be explained by Obama and Bush sharing similar philosophies on the security state, and there's a lot of evidence that supports that. That's not to say that the agencies aren't problematic, but rather that elected officials have been mostly happy with what they're doing, and that this is the reason why they keep doing it.

Where there were differences in policy between the administrations, we did see a change - for instance, in the use of waterboarding. It's just that these differences weren't as numerous as many people assumed.