Certainly he has violated his confidentiality agreements ( a civil liability ) and exposed information that is classified ( potentially a criminal liability ).
And it's possible for rational people to think that he may be doing things that are morally justifiable even if criminal. Where most people who think that investigating systematic acts of lawbreaking ( and wholesale collection of private metadata absent criminal suspicion from private companies by __any__ .gov qualifies as such on first examination ), may believe that those who bring such acts to light should be spared punishment because they are acting in defense of the greater good of society.
It is healthy for us to be reminded that our naive moral calculus is only loosely mapped to our system of laws.
"if such disclosure is not specifically prohibited by law and if such information is not specifically required by Executive order to be kept secret in the interest of national defense or the conduct of foreign affairs;"
Also www.aclu.org/pdfs/safefree/disavowed_report.pdf (Page 10)
You find a Top Secret folder lying on a park bench, with records of a horrific crime by a respectable cabal of executive, judiciary, and legislative branch members. The president and his staff, a few FISA judges, and some high-placed congressional cronies have conspired to brainwash everyone with a magic potion, and seize total dictatorial control of the US, then the world. They are using the loose oversight of post-9/11 homeland security to get away with it.
So is it a crime to send that proof to Glenn Greenwald? I'd argue that there are theoretically classified documents that it would not be a crime to make public, and all you can say is Snowden's leak doesn't fit the bill.
"Whoever having unauthorized possession of, access to, or control over any document, writing, code book, signal book, sketch, photograph, photographic negative, blueprint, plan, map, model, instrument, appliance, or note relating to the national defense, or information relating to the national defense which information the possessor has reason to believe could be used to the injury of the United States or to the advantage of any foreign nation, willfully communicates, delivers, transmits or causes to be communicated, delivered, or transmitted, or attempts to communicate, deliver, transmit or cause to be communicated, delivered, or transmitted the same to any person not entitled to receive it, or willfully retains the same and fails to deliver it to the officer or employee of the United States entitled to receive it"
" Whoever knowingly and willfully communicates, furnishes, transmits, or otherwise makes available to an unauthorized person, or publishes, or uses in any manner prejudicial to the safety or interest of the United States or for the benefit of any foreign government to the detriment of the United States any classified information—"
In the example I have created, while wildly fantastic and unbelievable, the information does not relate to national defense at all. It is simply a record of a conspiracy committed by powerful people, which was "classified" by those same powerful people.