It really isn’t a matter of a legal basis for secession. In essence it is what the colonies did when they declared their independence from Great Britain. I tell my students that there were two great questions about the War Between the States, one moral, and one political. In order to avoid any accusations of racism or political bias, I immediately concede that on the moral question of slavery, the South was undeniably wrong. However on the political question of whether or not they had the right to secede and their vision of government as provided by the Founders, I get my classes to rethink what they have been taught before and take another look at the problem.
What it is going to take I think is a continued “train of abuses” as Jefferson so eloquently declared. My students are always appalled when I explain to them the tax rates that caused colonial Americans to rebel. When I explain to them real reason behind the Second and Tenth Amendments. The Declaration of Independence is the political scripture that states will need to look to, not some legal decision that had nothing to do with actual issues at hand. (Texas v. White). This is just my .02. I would love to hear from really well read and articulate Freepers on this, like NathanBedford.
I suppose the question of authority in international relations is a matter of power.
The Confederates had the legal authority to secede, merely by revoking the ratification of the Constitution, which is what they did, but, as history proved, they lacked the power, and therefore their legal authority was revoked de facto and ex post facto de jure.
Similarly, the question of Texas' secession--or Hawaii's--is a matter not of law but of power.
I seem to have answered my own question.