Ruby, I am curious...
and please don't take this as any sarcasm because i'm not trying to flame you....
In your opinion, taking the above into consideration, should the slave owning south have had the same rights to shape their own lives and their own nation? To what extent would you think it appropriate to interfere if a nation, say Mexico, were blatantly active and prosperous in the slave trade? specifically the sex slave trade? I'm trying to gauge how absolute is the right to autonomously shape the lives and nations of a people.
I understand your question, its a good one and will always come up...When is it ok to interferre?
This has to be one that is always carefully weighed and when we do determine to interferre on a humanitarian basis we must make sure not to inteferre in the community carrying out its political will (establishing its own govts, laws, customs etc). There have been many scholars who believe you should NEVER interferre, even in the case of humanitarian causes (which are always suspect and its hard to find even one example in history where a nation would do so for purely altruistic reasons).
The example you give is a good one, but this one was determined by the people of the nation internally in a civil war. Although I also would argue it was the souths RIGHT to suceede and become their own political community. The slave trade itself was not domestic, it went OUTSIDE its borders and captured foreigners to become slaves and on that basis the international community could step in and rescue kidnapped foreigners and ancestors as well as stop them from invading other lands to kidnap more.
On mexico, if they were to engage in a sex slave trade and prosper and this was a legal act (mexico making it legal on an official basis). I would consider it a deep violation of human rights but it would have to be the community itself that stood up to stop it. I would agree with other deterrents such as cutting of diplomatic ties, trade etc to nations who are in such violations. We have another option, we could join the world court and establish national human rights and be able to bring leaders who violate them to court for such things and leave nations to work out their own political lives and futures without invasions or occupations.
Here is the bottomline though, IF it is determined (and there are cases it could be) that a foreign nation should interferre to help people inside a foreign community, then it should be limited to stopping a human rights violation AND NOT go beyond. The foreign community cannot change its borders, be part of selecting new govts, create new laws etc.
Can you find an example of a purely altruistic act such as you are describing by any nation in any time of history? The reason I ask this of you is to make the point that we are asking for somthing that dosent really happen and if we are to be honest, the humanitarian cause is more often the EXCUSE or rationale given for a nations own selfish reasons...thats the trap.
Keep in mind that all governments have a duty to protect the lives of their citizens and only put them on the line to benefit their own society....is it even ok to ask people to give up their lives for another nation while not benefitting their own in any way? Is this the right of our leaders? These are also questions that arise.
Enjoy living in all these poor governments who have NO CONTROL OVER ANYTHING IN THEIR OWN COUNTRY......EXCEPT.....their very own government lives in the most opulent of all living.......But........that is the fault of.......someone else..........
Trying it again won't come as a shock to them. 
I am sure they are willing to protect themselves and based on your comment above THEY WOULD HAVE THE RIGHT TO PREEMPTIVELY INVADE THE UNITED STATES OF IRAQ (oops, I meant America). 
We have repeatedly supported terrorist organizations especially when we want these organizations to control their countries. These people don't want to hear the truth about what we have done and why we do it (i.e., what was the real reason we nuked Nagasaki and Hiroshima). When people fanatically believe in a cause they are able to commit some of the worst atrocities and justify them. This is why our government supports terrorists in different countries and try to prop them up and legitimize them as the government of their countries. In short, "the end justifies the means." This is the kind of attitude that all terrorists have including Osama bin Laden. Why the hell did we support him when we knew what he was? The answer to that is obvious: "the ends justified the means."
