The one objection I have to Kerr's otherwise excellent article is that he entirely ignores the policy aspect of Prosecutorial discretion.
Lots of people openly violate federal criminal laws. An enormous number of them, like Swartz in this case, do so non-openly but in a way that a trivial amount of investigative effort would reveal. The vast majority of them are not charged.
This selective prosecution is a de facto policymaking process. It's not enough that the prosecution not be an abuse of discretion, it needs to also be good policy. Saying that the law needs to be amended to stop enforcement might be the technically proper thing to do but it's not the only option open to opponents of the law.
No offense but it's hard to call this "selective". If Aaron had simply given up during one of the first few roadblocks put up that would have been the end of it. No calls to the police, no charges, no nothing.
MIT didn't even know it was Swartz until he stupidly re-entered the network closet for the second (or third?) time and finally got caught by the police that MIT had to make special arrangement to have standing by.
If you make yourself the object of a inter-agency sting operation then it's a pretty fair bet that there might just be charges coming en route when you get caught.