"How was the Kansas-Nebraska Act challenged by Dred Scott?"

Why would you declare the Missouri Compromise Unconstitutional in 1857, 3 years after it was repealed in 1854 by the Kansas Nebraska Act? There was no point in doing that was there?

Except to send a message that simular legislation, which tinkered with the constitutional process of the Admission of States, could also be ruled as unconstitutional. I think that this was an indirect way of making a statement from the bench without addressing those pieces of legislation and the general conduct of Congress in an overt manner.

In any case all of this tinkering with States admissions and other legislation passed by congress during the 1850's did not go unnoticed by the public. And certainly in the South it was viewed as attempts to circumvent the Constitution and due process.

Which was my point in the first place. It created the Atmosphere of distrust of the Government, which lead to the decision of first South carolina to Secede from the Union. And then later when Lincoln tryed to force South Carolina back into the Union it was the icing on the cake for 6 other states. And then the called for 75,000 volunteers which caused 4 more States to secede.

Arkansas is a rather unique example of what I am talking about. The only reason that Arkansas was a slave holding state is because it was admitted under the 1820 Compromise as a slave state in 1836 to balanace Minnisota admission, Arkansas being below the 36^ 30' parallel line.

In 1860 only 20% of Arkansas' population were Black, not all of these were slaves. That means that less than 10% of the Whites in Arkansas owned Slaves because many of the slave owners had 30 or more slaves. Hence, it would be hard to have a slave owner population larger than the percentage of the slaves. If there was a state that became a part of the Confederacy which would have probably outlawed slavery if it had been given the chance it was probably Arkansas.

Arkansas Held three (3) secession convention during the period from January to May of 1861, The first two of those secession conventions ended with the delegates voting to remain in the Union. Certainly they did not pass those two votes with the idea of fighting to keep their slaves for the minority of Slave owners in the states.

It wasn't until until the third Convention in May of 1861 (well after Fort Sumter) when Lincoln called for 75,000 Volunteers that delegates became so upset with Lincoln's demand that they passed their Secession Ordinance and joined the Confederacy, the same as Tennessee, North Carolina and Virginia did also.