The really scary thing about the NSA scandal

....as described here, is not simply that the NSA may be doing domestic spying in direct contradiction of the 2001 law that authorized data retention for contacts with foreign phone numbers and emails.  It is not merely that any mere citizen could find themselves in trouble with the law based on a rough inference from these records.

It is, rather, what Mr. Snowden noted about the possibility that the NSA could be bringing up emails of the President.  If indeed this is the case, then I would presume that any high official who would want to hold any government agency accountable could find himself (herself) being discreetly shown a message they sent that could get them in trouble.

In short, it's a system that, once properly abused, enables whoever controls the leashes to the NSA to become a shadow government with no one the wiser.