"I, sitting at my desk, certainly had the authority to wiretap anyone, from you or your accountant, to a federal judge, to even the President."
Meanwhile, the way his wording sounded to me (and is quoted more often elsewhere) was:
"I, sitting at my desk, certainly had the authorities to wiretap anyone, from you, or your accountant, to a federal judge, to even the President if I had a personal email."
The differences are the pluralization of authorities and the addition of the conditional-qualifier "if I had a personal email".
Of course people speaking in an unrehearsed manner may mix up tenses, pluralization, and speak with imprecision as they shift between thoughts and chosen emphases. But I suspect those portions of the quote Reuters messed up were significant.
First, it sounded to me like 'authorities' was likely a term-of-art in his intelligence-analyst line of work, meaning specific rule-artifacts in the access system, representing a mix of 'proper credentials' and 'suitable legal/system authorization'.
After all, NSA defenders have given the impression that even though there is a massive amount of data collected, including on US citizens under no suspicion, it's OK because those records sit idle, never looked at unless and until the right conditions are met.
I have a hunch those conditions are called 'authorities'. So when you've got records on individuals A, B, and C, and your algorithms tell you A & B are 51%-plus likely to be US citizens, but C is 55% likely to be a foreigner, well, you can use the longstanding 'authority' allowing analysts of your grade to do warrantless surveillance of foreigners, to start pulling things up on C, from anywhere and everywhere (including previously-bulk-warehoused call recordings, colloquially 'wiretaps').
And then when you see that C has been emailing B, that alone, or perhaps the contents of those messages, might be enough to activate another 'authority' - suspicion, or association, or content-pattern based - which then allows at least a peek into B's records. Perhaps that peek confirms B is a foreigner - now the identity is marked that way, and it's all wide open. Or maybe the peek shows B to be a citizen... well, now you've got 1 week to ask the FISA court for a warrant. Better read fast! (Open question: if NSA decides after this 'free look' they have no interest in continued surveillance of target person B, does the warrant for retroactive permission ever get requested? Are there any records or repercussions from the 'free look'?)
Of course, the visibility of some target-records might be over-determined: multiple active 'authorities' all allow viewing. Others might require some "good at the keyboard" analyst creativity to activate: is there a past-travel, likely-associations, prior-suspicious activity, etc. 'authority' that could be applied? Still other 'authorities' might only be available to more senior analysts: maybe targets who are themselves state/federal employees, elected officials, etc. have an extra sheath-of-privacy that prevents easy peeks by junior people using the most simple and elastic 'authorities'.
Which brings us to Snowden's other carefully-qualified bombshell: "…to even the President if I had a personal email." Let's say person B above is in fact the US President... perhaps using a separate personal email address. (There is of course controversy about officials having separate email accounts, but it's almost certainly a rampant practice – see especially the recent Petreaus affair and allegations administration officials in the EPA, HHS, or Labor department have used secondary addresses, sometimes under alternate names, for official business or leaking.)
Now using one of the myriad of 'authorities' a skilled analyst can utilize, they can start pulling up warehoused records about B – the President himself – possibly including previously recorded telephone/VOIP discussions linked with the B identity (aka 'wiretaps').
I wonder, then, were 'a federal judge' and 'the President' just vivid hypothetical examples? Or maybe Snowden actually pulled up, or heard that his coworkers pulled up, private conversations of a federal judge or the President himself, using 'authorities' that weren't especially hard to bootstrap, given the surveillance system architecture.