Nice idea, but it aint going to happen.
Maybe if the U.S itself impeached him etc, he might eventually stand trial for something or other under international law, but that would only be without the weight of the US behind his back. Unless the states themselves wanted him done, they would just veto anything the UN ever said about it. Failing that, the US would have to get slapped back into the 18th century, militarily speaking, become an occupied nation, and then Bush forcibly removed by the invading force. Y'know, like in Iraq...
I dont think his standing in this whole Skulls and Bones thing would help either, veto notwithstanding. Thats a peculiarly american "old boy network" that has little influence abroad. (After all, the Uk alone is a lot older, and has many much more antiquated "old boy networks" all of its own.)
Any way you look at it, I doubt that Iran will ever be in a position to carry out a trial, unless Bush is dumb enough to get his ass captured visiting iraq or something. (having said that...dumb..maybe.. just maybe..)
Still.. we can live in hope I guess.
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"There is a time when the operation of the machine becomes so odious, makes you so sick at heart,
that you can't take part" [Mario Savo, 1964]