The War Between the States Sesquicentennial—State Sovereignty
One of the most preeminent American constitutional scholars, Confederate Vice President Alexander H. Stephens, saw that continued recognition of sovereignty residing in the States was essential for the Union to be perpetual. Destroy this and the system would degenerate.
Bernhard Thuersam, Director
Cape Fear Historical Institute 
The War Between the States Sesquicentennial:
State Sovereignty Regulates the Entire System:
[Mr. Stephens remarked] “I did not attach any serious importance to the fact that the equality which had for so long been maintained in the number of the non-slaveholding and slaveholding States no longer existed. It is true that the loss of that equilibrium, or balance of power, as it was called, caused many at the time to come to the conclusion that the slaveholding States could not, with safety to themselves, remain longer in the Union without some additional guaranty. This was the belief of Mr. Calhoun.
But the only true equilibrium, or balance of power, in my opinion, under our system, which it was essential to maintain, was the recognized Sovereignty of the several States. This was the all-powerful check against aggression upon the rights of any State. This was the complete regulator of the entire system.
This was my view on the admission of California, as it was on the admission of Oregon. The result showed that, so far from the admission of those States working injuriously to the interests of the slaveholding States, by the loss of the balance of power, so called, California and Oregon were as strongly opposed to the doctrines of the centralists as the Southern States were.”
(Life of Alexander H. Stephens, Richard M. Johnston & William H. Browne, J.B. Lippincott, 1883, page 382)