"Crimes against humanity" mean to some people, crimes against the world --- yet as we have seen, a majority of Iraqis do not regard Saddam's crimes as being against the world; rather, they regard his crimes to be specific, against a couple "Arab neighbors" and against the Iraqi people --- mostly, murder.
Charge him with murder, and you'll get the death penalty, and keep him a little POS that all dictators' rank, they work so hard to earn.
Make the charges notorious and ridiculously large, and that will make a big man out of him, which is exactly what the terrorists want.