That may not be possible given the category of law he's charged with. Since his leak did damages to espionage programs that are undisclosable (under classified information law), prosecuting him fairly may not be compatible with the American system of justice as laid out in the Constitution. No real way to do it without building a "star court" with privileged access to classified information, that can therefore not be a randomly-chosen jury of his peers.

... which, one could argue, is a problem with the way the US runs espionage.