It is extremely likely that the US invasion of Iraq is an illegal use of force under treaty/international law. It can be characterized fairly as a 'war of aggression.'
Under the holdings at Nuremberg, that is a war crime. That is also one of the legal theories with which we nailed the Nazis.
A war of aggression is a crime against an entire people and that comprehends Crimes against Humanity by virtue of the wholesale death, carnage and destruction attendant to such an invasion.
Either we are a country that honors laws or we are not...nothing more than hypocritical monsters. I like to think that the US has the basis to be the best country in the world.
Treaties become part of the US Consitution once ratified by 2/3 of Congress.
Our Constitution is second to none. The Bush administration's repeated violations of the Constitution does great damage to our form of government and our global reputation.