I have always found capital punishment to be utterly repugnant. The idea that the state can have a right to take life feels like an abdication of the moral high ground and comes down to legalised killing. It is not done for defence but rather for vengeance, to sate a blood lust.
There can be no exceptions to such a position. Whatever Saddam Hussein has done, sentencing him to death is a state taking action to kill. It is declaring that people are potentially beyond redemption. That there is no hope in the world.