As far as Saddam's authority being legitimate, we actively supported Saddam in his early years in power, and recognized him as the legitimate leader of Iraq. Granted, the mistreatment of his own people would suggest that he has given up any rightful claim to a position of authority, but I do think that it is ultimately up to the people of Iraq to rise up against him--much like our nation's founders rose up against King George.
When we start getting into the area of questioning government authority, we cannot avoid wondering whether or not the government of the United States is legitimate. Sure, it was lawfully established under the Articles of Confederation and refined by the Constitution, but we can see throughout history that our government has moved further and further away from its intended role. The Constitution no longer has any meaning to those who govern.
I think a much bigger issue we need to address is determining the legitimacy of our own government. Can a government wage a "just war" against another nation while ignoring the more immediate threats it poses to its own citizens (e.g., over-regulation, over-taxation)?
I'm not saying that we should take up arms against the government. I'm merely pointing out that our government is hardly a "moral authority."
More evidence of the uselessness of the libertarians in the war on terror.
As to our support for Saddam in the early 1980s, it's frequently been said that the "enemy of our enemy is our friend." Back then, Saddam didn't seem to be the fiend he's turned out to be. But we also supported Iraq as a way to "balance" the Iranian regime. 9/11 seems to have changed a lot of conventional wisdom in regard to diplomatic strategy. Now, "balance" and "stability" are synonomous with "status quo." Why should the US as the leader of the free world decide to accept the "status quo," either in the Middle East, or anywhere else? "Status quo" means more killings, terrorism, more opporession in the Middle East. Saddam encourages and sponsors Palestinian terrorism, which is the greatest destablizing factor in the world.
For those Hollywood and garden variety leftists types who do not think we should take out Saddam, I have to ask, "Why not? What is it about Saddam you particularly like?" The old arguments don't work any more.