If you've never read the Confederate Constitution (and one could draw that conclusion from your comment), I'll be happy to provide a link to that neoConfederate organization, Yale University. http://www.yale.edu/lawweb/avalon/csa/csa.htm
Or, if you prefer a short summary, the Confederate Constitution (unlike the Yankee one) prohibited the importation of slaves from other parts of the world, permitted, but did not require, laws prohibiting the importation of slaves from the United States, required that slavery be permitted in any new territory, and protected property rights of Confederate citizens as they moved from state to state within the CSA.
I have read it, actually.
Thanks to x for the citation:
Article I, Section 9, Clause 4: No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed.
And there you have it. Slavery was so important to the CSA that they enshrined it in their Constitution. No state could pass a law prohibiting it.
As I said above, I'm sympathetic to the story of brave rebels standing their ground for freedom and liberty in the face of an oppressive federal government, but that wasn't what the CSA was doing. Unless you're talking about the freedom to own other human beings.