Apparently the deal is that after the death penalty was revived in the late 1970s, espionage convictions weren't just automtically subject to it in the way they'd been before. I found something showing James Trafficant trying to get it passed in 1989--probably in the wake of Pollard. It's definitely on the table today--here's the DOJ worksheet to decide.
Of course, the other problem with a treason charge is that what it is is very explicitly spelled out in the Constitution."Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court." Did Pollard levy war against the US? Is Israel our enemy? The latter, at least, is a question that I can't see any administration wanting to get into.
Right. For that reason, it would be almost impossible for Pollard to be charged with Treason and the only way is if they could argue that an enemy managed to get the information second-hand. Not only is that a stretch, but it’s hard to argue this because there wasn’t a state of war with virtually anyone at the time.
Come to think of it, I don’t know that any of the Soviet spies were charged with treason. A half-decent lawyer could easily argue that there was no state of war.