This isn't some low level aide. This is part of his inner circle. And unless there's some wildly unexpected explanation, it's pretty clear that we've got the worst case scenario for the Governor in terms of the political damage. I doubted very much that we'd see any email smoking gun. And it's still not from Christie himself. But it came from the Governor's office and I think the weight of logic (though as yet no direct evidence) at least says that Christie himself knew about the order and may have ordered it himself.
I see no credible way now for Christie to say he bears no responsibility for what happened. Responsibility doesn't mean knowledge or culpability. But one of his top aides was involved. So he needs to discipline or fire her or at least say it was wrong. (Perhaps he can say it's okay or that the emails are being misunderstood. But good luck with that.) Regardless, it will be very hard not to provide some accounting of who else in Christie's office knew about this or was involved.
It's not bribery or killing someone or a high crime. But it's vindictive and quite possibly illegal. It's almost the definition of an abuse of power. It won't sink Christie. At least not the evidence so far. But it will hang around his neck forever as that bad thing Christie's operation did that supposedly (depending on whether you're a friend or enemy) tells you who the real Chris Christie is about.
The Mayor of Fort Lee, the target city, says "I've been punished not for something I've done, but for something I didn't do. This is the behavior of a bully in a schoolyard. It is the greatest example of political payback." Mayor Sokolich is hardly a disinterested party and he's a Democrat. But based on this information, who can disagree with what he's saying?
Christie's got a big problem on his hands. Which is probably why he cancelled today's events to try to grapple with the story.