"The fact remains, southern leaders were perfectly happy to avail themselves of federal power when it suited them"

Well, yeah! That was the whole purpose of forming a Federal union, to facilitate cooperation between the states. It was never intended by the founding fathers to become an entity to which the will of the people was of no consequence.

I feel though that the fears of those who saw problems within an all powerful central government have been proved to be true. The idea of States Rights is being treated in this thread as some kind of smoke screen created by Southerners to perpetuate a myth. Such was not, and is not today, the case. Consider the words of Lord Acton in a post war letter to Robert E. Lee...

"Without presuming to decide the purely legal question, on which it seems evident to me from Madison's and Hamilton's papers that the Fathers of the Constitution were not agreed, I saw in State Rights the only availing check upon the absolutism of the sovereign will, and secession filled me with hope, not as the destruction but as the redemption of Democracy. The institutions of your Republic have not exercised on the old world the salutary and liberating influence which ought to have belonged to them, by reason of those defects and abuses of principle which the Confederate Constitution was expressly and wisely calculated to remedy. I believed that the example of that great Reform would have blessed all the races of mankind by establishing true freedom purged of the native dangers and disorders of Republics. Therefore I deemed that you were fighting the battles of our liberty, our progress, and our civilization; and I mourn for the stake which was lost at Richmond more deeply than I rejoice over that which was saved at Waterloo."