[JohnsonB]

It's his intent that matters, who's computer he supposedly was trying to gain property from only matters once you prove he was using false pretenses. IP/MAC spoofing is not intrinsically a fraudulent activity, and in the context of MIT's campus from where he could access JSTOR, there's no reason to assume Swartz thought he wasn't allowed to do a bit of scraping, IP blocks for low traffic's sake notwithstanding.

[brazzy]

Sorry, but that's unmitigated bullshit.

He didn't do "a bit of scraping", he tried to download the entire archive. On a guest account at a university he had no relationship with. Over a period of months. He was blocked with increasingly wide-reaching measures and reacted with increasingly elaborate circumvention attempts, culminating with a laptop hidden in a closet.

His intent was very clearly criminal.

[Symmetry]

IP/MAC spoofing is not intrinsically a fraudulent activity

No, it's not. But doing it to get around people blocking your computer is. Likewise firing a gun isn't illegal, but attempting to hit someone when you fire a gun is illegal even if you miss. Intent figures into guilt and inncense in most matters of criminal law.

Swartz clearly knew that his IP address and then MAC address were being blocked specifically. You could argue he might have thought that it was just traffic shaping, but that wouldn't explain the MAC block.

EDIT: Clarified by adding 'criminal' in front of law.