From the article:
One source of concern is the jury. Snowden says his leaks revealed an unconstitutional and undemocratic system of surveillance. Polls suggest that many Americans agree. Even if the judge instructs the jury to set aside its views on the rightness or wrongness of Snowden’s acts, there is no guarantee it will. Jurors might be tempted to acquit Snowden, not because they believe he is factually innocent but because they believe he was morally justified.
It has happened before—in England. In 1985, Clive Ponting looked destined for prison after leaking Ministry of Defence documents that called into question the official story of the Falklands War. Ponting fessed up to being the source. The jury voted to acquit him nevertheless, and in so doing helped catalyze a movement to liberalize the laws against unauthorized disclosures.
For a judge to instruct a jury like that is deceptive and criminal. Well, most judges regularly engage in criminal activity (fraud), but that's another story...
The formal phrase for that is "jury nullification
". It's a well established part of common law. However, judges never instruct juries properly so it is rarely used - juries are rarely aware of their right to nullify. (The general concept is called "nullification" and in the US also extends to individual states to nullify any federal law - i.e. the 10th amendment.)
In short, any jury can find any defendant not guilty completely in contravention to whatever the law is. i.e. ALL juries can vote with their conscience. They are under ZERO obligation to listen to the judge's instructions.
So, if you are called to be a juror for let's say a marijuana possession charge, you can find the defendant not guilty irrespective of whatever the law is. (This applies to jurisdictions that are based on common law, and not something like Napoleonic law, etc. So, it includes Canada, the UK, Ireland, Australia, etc.)
If Snowden were brought to trial, and the jury were informed about their RIGHT to nullify, does anyone thing they'd convict him?
Well, if the prosecution used its infinite number of juror dismissal tickets to get the exact right jury to convict, then probably they would. Barring that gross abuse of power though, would a normal jury convict if they were informed of their right to nullify? I doubt it.