This point is extremely important and is what Snowden continuously returns to. In yesterday's Q&A he said "policy is a one-way ratchet that only loosens." This idea is critical to having an intelligent debate of the issues at hand.
There's infinite bad things that can be committed by anyone, from the government or otherwise, where the only thing preventing it is policy and procedure. The only thing preventing an Apache helicopter from firing on schoolchildren under order of the president.... is policy. Theoretically, as commander-in-chief, the president has the authority to order that, right? But what's important is that he doesn't. What's important is there's policy that prevents it.
To be fair, it wasn't apache helicopters.
A better method of prevention would be to not build Apache helicopters.
It's easy to say someone else should unilaterally drop to their knees and bow the head.
Until Utopia arrives we have to make sure our current reality is as optimal as it can be.