Deliberately breaking into private, protected data streams. There have to be some laws here that would be broken if this were not a protected government entity (which is a sign that the laws are broken if they don't apply to all entities). And it appears there may be laws that have been broken even given this is the NSA.
The laws are largely irrelevant. The current administration cares as little about the rule of law as the previous one did, at least in terms of how they apply to the administration. And even if they did care about the law, they'd simply claim that in this case they do not apply for reasons of national security; based on a secret ruling from a secret court, etc.
So, do these people really think there are any limits at all?
None whatsoever. The only potential consequences are political, and the American voter has proven to be very, very lenient when it comes to this sort of thing. People will gripe, but not much more.
Is the world really such a dangerous place that we cannot survive "safely" without this level of intrusive microscopic examination of us all?
Even if it was, this sort of thing would be over the line.