In a liberal democracy we have a moral duty to follow the law. However if the law is seriously against our conscience, we can commit an act of Civil Disobedience.
But after committing an act of Civil Disobedience, we have an equal moral duty to turn ourselves into the Police.
It's plain Edward Snowden had a moral duty to break the law because it was seriously against his conscience.
But he failed his moral duty to turn himself into the Police.