Unfortunately, it is very unlikely that the victor's court that tries Saddam Hussein will stand as a beacon of rule by law nor is it likely to spearhead the establishment of a democracy in Iraq.
The problem with all expost facto laws is that they leave a legitimate claim that the case is an example of might makes right.
The best court for handling cases of attrocities committed by a government against its people is the ICC. By nature, the ICC is always politicized. I mean, the only way to try a king involves first overthrowing the government. Overthrowing governments takes a concerted effort. Those governments that do get deposed will still claim that they are victims of a victor's court...however a healthy ICC could at least establish the precedence of law in the trial itself.
Unfortunately, the ICC destroyed itself. Avocates of a world government had hoped that the seed of an ICC could grow into a court that stood above all courts. As such the ICC was playing games like changing the wording between the documents approved in the Rome Accord and the documents sent to ratification. A world court that answers to no authority will gradually expand its rulings into every aspect of life. An ICC limited to trying rulers of state would be welcome. One that stood over the Supreme Court in any matter with international effects is not.
Clinton was correct in not signing the accord, unfortunately Bush blew a historical opportunity to get the ICC back on the correct track. Instead, Bush played with absurdities like complete immunity from any law of any land in Guantanimo Bay and the various post 9/11 wars.
Reading several of the different web sites about the ICC, it appears that the US military is one of the biggest opponents of the ICC. With a belief that they are incapable of doing wrong, the military is freightened about the prospect of other agencies trying US soldiers. Quite frankly, I think they would be happy to have someone else try soldiers that go overboard and violate human rights.
Even if crimes by military personnel is a tiny fraction of crime that occurs on US streets, there will be a significant number of crimes needing to be tried after military actions that involves hundreds of thousands of soldiers.
We can only hope that someday we will have a US administration that truly pushes solutions to problems of rogue governments. As it stands now, we live in a world where it is okay for Sudan to slaughter citizens by the score. The only countries that might ever see retribution are those that threaten US economic interests.