I thought the track record of the US Government on the matter was pretty clear:
1) Write down the law
2) Break it
3) Retroactively make the violation legal
Wrt to what oversight exists, well... the fact that they have no idea what material Snowden took with him is telling. But that's not what I'd be the most worried about. How hard would it be for the White House to ask information about a specific individual for "national security" reasons?
> But either way, you say that the consequences will at least be public in other scenarios. But that's not really true either. People get shot every day in this country; how do you know that any given shooting wasn't from a soldier?
I'm not a US citizen, but I would think murders are investigated by the police. It's usually difficult to hide.
> How do you know when the government lets a contract that they actually fully complied with the Federal Acquisition Regulations?
I suppose there are audits? Not to suggest that abuse does not exist, but I assume there is some oversight.
> How do you know that when a Congressman votes against his normal voting habits, whether that vote was due to his conscience or due to someone else's wallet?
You certainly don't, but you can make an educated guess.
I'm not sure what you're trying to say here. That the NSA doesn't need any form of oversight, and can be 100% trusted with the power to snoop on everybody belonging to any country (knowing - in case you thought "I don't care about these dirty foreigners as long as they promise not to look at US data" - that nothing prevents them from asking another Five Eyes member about your whereabouts without breaking the rules)? From the same government which gave you Guantanamo, extraordinary rendition, warrantless wiretapping and extrajudicial executions-by-drone? Their definition of legality is terribly elastic.