. NSA, CIA, and FBI don't keep the government in check, they're extensions OF the government; FBI is also basically police, btw. I think you were thinking of the judicial branch, though that wouldn't make sense either as they're the government too. All that can really stop the government are people like Snowden who basically ruin their lives to reveal the truth. But even then, we'll never know if the government truly stops doing all this crap, will we?